cpu computer water-cooling watercooling water cooling cool Always try to improve society rather than just take from it. Until then, lawyer stuff. Those using this information do so entirely at their own risk. Errors and omissions excepted. Contents subject to change without notice. All material herein is subject to copyright, patent and other intellectual property rights. All rights reserved. Copyright (C) J.Partridge. 2004.

Please note: In these days of litigation taking the place of natural justice, it is necessary that those wishing to read the monograph must understand that they must not, nor will ever hold the author responsible for any damage or injury. This is because the author does not want a parasitic lawyer coming on heavy because some damn fool thinks he or she is some brilliant engineer, or stubbed their toe and wants a fortune because they happen to be stupid.
I don't mind putting my knowledge on the web, after all, we should help make a better world, but as lawyers get richer, society gets poorer. So Please use your vote to keep lawyers out of politics. Have a nicer day :)

As just one of tens of thousands of science graduates and engineers being wasted in Britain. I write this website to help others and as a C.V. - hoping it may lead to a job. Gizzajob.

Always remember that real engineering is doing for a fiver, what it takes a big corporation to do for a thousand quid.

I first got into cooling computers when the large custom chip in my BBC 'B', used to overheat and cause the computer to crash. I soon started developing coolers and discovered thermal paste 25 years ago, along with alloy radial cooling fins and small fan systems. The biggest thing I learnt is just how easy it all is. Modifying computers is still fun.

Beyond the hype:

The other hype is that the more you spend, the better the system, which is total and utter rubbish. The best systems I know cost pennies.
A friend who builds high specification computers recently put a top commercial water-cooling system in his best computer and it did very little to improve the running temperatures. The water-cooling was in my opinion, failing in the simplest design needs and mostly a waste of money. I would happily replace most commercial systems components.

I have friends who still refuse to accept the underlying physics, but rather prefer to accept the hype and high price tags. This is not for them, but for those who prefer to try building something better, rather then to open their wallets.
I truly dispair of much of the fancy crap they often buy for massive costs and yet have no useful advantage. The poor level of schooling today has led most people into knowing very little and all too often taking hype and bullshit as the truth. The ability to think for oneself is lost in modern Britain. For most people, only the big shops and internet catalogues have the modern form of truth: the more you spend, the happier you will be.
If you want to buy a fancy, bullshit computer, then stop reading now, grab your credit card and go surfing.

If you have an open mind, then you may wish to read on.

This web page is large.
It starts with a lot of description of how present systems can be improved.
If you want to build your own, then the later sections will show how many different ways can be achieved for no money and with far greater style then the present commercial junk.
Building your own pumps, radiators and cooler headers is also mentioned later. including a few radical direct water cooling designs which are cheap to make, but hard to design correctly.

About watercooling.
Water-cooling is simply a means to move heat from one place to another. Luckily, water is a superb transport medium, ideal for regulating beautiful planets. Water it can absorb a great deal of heat energy without raising its own temperature by any vast amount. This can then be transported to a device which can remove the heat energy out of the system.

Water-cooling is in my opinion, open to far too many myths. Admittedly water-cooling of home computers is definitely in its infancy, as is much of the computing world, so many myths have naturally built up.

One of the biggest myths is the amount of coolant flow which is often greatly overestimated.
I started by calculating just how much water is needed to cool a typical 70 watt processor remaining around 45 degrees. This assessment of the basic arithmetic led to many insights and design possibilities.

Please note that there are thermodynamic booby traps in calculating such systems. The first is that the ambient air temperature in the room is the limiting factor and any system temperature must be above the room temperature. If you live in a centrally heated, double glazed house, then expect the overall temperature of the system to be higher than most others, as you cannot remove so much heat in a warm environment. If you live in a draughty cabin in the Arctic, then an identical system will run a lot cooler, as the heat difference between the room air across the radiator and the warm coolant will be able to transfer far more heat.
Just speeding up the radiator fan will not make things cooler, nor create a great difference in temperatures once the system has settled down.
The laws of thermodynamics state that you just cannot cool down below the temperature of the room. To learn more, check out the concept of entropy. Ask your science teacher, as it's basic science.

I originally thought the many experts out there knew their stuff when they said a pump needs hundreds of litres per minute, but gradually doubt crept in. As described later, I built a small pump for nothing, which pumped 1 litre per minute at 12 volts and half a litre at 5 volts. Surely this pitiful little pump was of no use in a computer.

As part of a four year engineering apprenticeship, I happen to have studied thermodynamics, so decided to do a little basic maths. In the second part of this monograph, I've kept the maths simple, so all can follow.
It turns out that the fancy pumps are not needed. Indeed, even my little test pump could be run at low speeds. If the experts got the coolant flow wrong, I wondered what else did they may have got wrong. The answer was of course is that they got it all wrong.

Looking closer, it turns out that the experts don't know their subject very well and prepared to sell selections of poorly matched, or inadequate components which will indeed water-cool a computer, but not very well. They are like most British experts, good at taking money, but not good at physics. They make a lot of money because no one seems to bother to understand what they buy. Even the hobbyist computer magazines with articles on water-cooling make some massive bloopers.
With poor education, we will continue to buy crap. British education flounders due to poor maths and science teachers. Half of British maths teachers are not trained as such. Sorry kids, the likes of me with B.Ed and B.Sc, are out there applying for jobs to make learning far more interesting, but being white, male and over forty, we are considered fit only for shelf stacking. Don't blame the kids, nor the thousands of science teachers looking for work.

Trained as an engineer, fitting superheated steam systems, a draughtsman and HNC refrigeration, steam generation and central heating, a science degree and such like, blah, blah blah, and even a couple of the totally crap GNVQ's for my sins, I've noticed many computers with water-cooling and all seem to have less than ideal set-ups. The many problems seem to occur with poor plumbing and its consequences, some no better than air cooling and a few that are actually worse. I could easily see a few simple ways to improve such systems. It really is not that difficult with a little background knowledge. (As I was highly commended for my curriculum and lesson plans during my B.Ed studies, I've written lesson plans for 14 yr olds as a set of six technology lessons on heat, with three different water cooled computer systems which can be made for pennies, to allow the pupils to make working measurements and learn about heat, basic thermodynamics and a modicum of engineering. The lessons plans are available by email.)

To prove the point that water-cooling can be done much better and a blatant rip-off, much of the following is done for no cost other than a little time and effort. Be it science or anything else, I don't accept the excuse that money is a barrier to making the best computer, nor a barrier to making the best pupils. (Making projects for pennies is part of a many Brit teachers jobs, as there is no working money in our education system, so the better teachers scavenge and teaches the pupils to scavenge if they want to learn more, than just passing exams.)

Having recently studied a GPU heatsink from a top computer cooling firm, well, not so much study, as to laugh at it, I was appalled by the poor design and atrocious build quality. The connecting pipes cause so much restriction to the flow because the cross sectional area was less than half of the pipe bore. The metal body was poorly designed and made. I just would not want this level of build in any of my systems for fear of it failing. Simply not acceptable.
If you are going to spend three figures on a CPU and another three figures on a graphics card, then at least these expensive components deserve something genuinely decent.

This webpage does NOT include is how to spend money.
What is does include is how to use your brain and hands.

As you read through, try to understand the underlying thinking behind water-cooling, so you can do it properly, or at least a lot better than done by many. My last friend who bought a water-cooling kit, soon removed it because it was not very good, yet it was from one of the better manufacturers.
Don't get stung like him, start to learn what is happening, and how to do the job sensibly and effectively. This and many other ideas are available as complete teaching projects with lesson plans and homework etc, for secondary schools, as part of my teaching studies, so if one day, you ever get me as a teacher, expect technology and science to be a lot more fun.

Let's start with a few simple considerations.
Decide if you need water-cooling; perhaps a hot running processor, or a small case, or overclocking. If not, then simply make your life easier and save the hassle and your money. Air cooling is not perfect for getting temperatures very low, but for most users and most computers, air-cooling is perfectly adequate.
A small case should not run hot, even with air-cooling, as you should be able to control the airflow easily. I build very compact cases and they still run no hotter than full towers. So check the internal aerodynamics of a small case before resorting to water-cooling.
From assholes driving 4x4's on the school run, to full tower computers, bigger is not always better, merely an excuse for incompetence or not understanding the point adequately.
Try some cardboard corn flakes packet and adhesive tape to improve the airflow first, it's a lot cheaper and far more reliable than adding more, expensive fans.

As to silicon, always remember that if you want to run faster, get a faster processor and graphics card, it really is that simple. As Harley owners say, 'there ain't no substitute for more cubes'.
If you can't afford more cubes, or you have all the cubes that are available, then it's time to tweak what you can afford.

Water-cooling is now considered a serious option as overclocking utilities are often supplied with the better graphics cards and motherboards.
Please remember that much overclocking is NOT due to a hotter chip, but because the silicon manufacturing process is giving high outputs of almost perfect silicon, and so some chips have to be down graded as slower, just to fill the market niches. - Sometimes the GPU is high spec, but rated much lower and will overclock without hassle, especially if it's an end of the line processor, where the fabrication is almost perfect.
Other systems are crippled with poor memory so that overclocking the GPU is a waste of time.
Likewise, a fast CPU with moderate graphics does not make a good games machine. By choosing the right GPU or CPU and memory, you can have a perfectly good, much faster item for standard prices and water-cooling is not always needed.

Always know the bottom line and starting points before venturing forward.

Assuming you have a real need for water-cooling, then here are some incredibly simple facts that some builders never seem to understand.

Water is a superb transport medium, but merely carries the heat from one place to another.
The amount of heat water can carry is phenomenal and far better than any normally occurring fluid on this planet. If using water temperature control with oceans is good enough to keep this gorgeous planet under control, then it's good enough for a computer. If there is a God, then he/she/it should be phenomenally proud of the power of water.
Water-cooling is superb and apart from refrigeration systems.

The amount of heat transferred depends upon the amount of water in contact and the difference in temperature. The greater the heat difference between hotspot and coolant, the greater the amount of heat that can be transferred per unit area in contact with the water passing over it. For a set difference in temperature, then the greater the coolant flow, the greater the amount of heat that can be transferred in a system. The cooler the coolant, the cooler the CPU.

But the little area between coolant and CPU or GPU is where the game lies. The rest of the system is to get this small hot spot as cool as possible.

You do not need to run a processor at sub zero as it is designed to run happily at up to 70 degrees, so this is all you need to play with. Overclocking yet running at 40 degrees is a happy piece of silicon. Running at a few degrees above room temperature is an almost perfect system.
Sub zero is theoretically better, but for playing games then this is overkill, as the chip will still generate heat, so push it by all means, but don't worship it. Sub zero is for posing in the pub with your friends, - if you have any friends after building a refrigerated computer. Therefore you must aim to present the hot CPU with the coolest water to be able to transport away the maximum amount of heat and do so sensibly.

Removing heat from the coolant is usually done by a radiator by transfer into an airflow.
Always remember a fundamental part of this game: The radiator cannot reduce the coolant temperature down to the ambient temperature. (of the room).
The better the radiator, the better the system. Poor radiator, poor system.
A poor heat removal system will always make the rest of the system equally poor. Unless all parts do a good job, then the whole system will be poor. - Your coolant chain is only as good as its weakest link. The radiator is the weakest link, - if it cannot remove the heat, then all the other parts are worthless. The vast range of radiators and how to make and modify them is discussed later.

High or low pressure systems.
Many commercial systems use a sealed system which has high pressure flow, more so when the enormous flow rate is advertised. Other systems run at atmospheric pressure, usually employing a vent system.

Water-cooling systems do not need high pressure to flow, but it is the amount of coolant passing which can improve a system, but that does not mean a system pumping twice as fast will remove twice the heat, - far from it. The system will settle down to its happy system, as long as there is some coolant flow, be it reasonable flow or much faster.
The heat transfer of the CPU header is by its very nature restricted to the heat flow through the metal, and as such, even flowing the contents of Niagara through it, will only allow a certain amount of heat flow to be transferred.
Any advert touting high coolant flows, is in my opinion, utter crap.
Getting the coolant matched to the heat flow is the way to make an effective and sensible system. It is for this reason that most CPU headers use copper or aluminium casings, as these have high heat transfer rates.

Cars have a pressurised system, but only to reduce steam build up from a system which must run close to boiling point. Computers should never get anywhere near such levels of heat, as the CPU should never get hotter than 75 degrees, as your silicon can fry at around 90 degrees. If you run your coolant hot, then it canot cool the CPU as there will also be a poor thermal increase in the area between the coolant and the silicone die.
The point of water cooling a computer is to keep the silicone die temperatures safe or lower; water-cooling a computer is not the removal of heat to simply prevent a car engine from melting, but cars can get away with running high pressure systems close to boiling, as the engine does not fry at 90 degrees. Indeed, a car engine uses a thermostat to keep the engine running about 60 degrees, as this is where the engine is optimised to run, with warm oil in winter and good combustion from a warm engine. Computers should run at much lower temperatures.

A coolant design with small bores will need higher pressure to get around the system and also need to pass the coolant faster than a slower, larger bore system. All other aspects being equal, large or small bore systems could both transport the same volume of water and transport the same amount of heat. A little increase in bore and fewer restrictions can make for a far more reliable system.
Lower pressure usually equates to fewer leaks and greater reliability on a less stressed pump. Water and electricity are not the happiest of bedfellows. Therefore no one wants a leak, or a cooling design which could cause damage to the computer if it should leak. Therefore a low pressure system would be preferred. All my water systems are vented.

Water is heavier than air, so any bubbles will want to flow to the highest point in the system unless blocked by an entrapment area. A well designed system will use this to advantage to get rid of any air. Air in the system means contamination and lower heat flow.

The last thing that many forget is that pipes should always be neat, but they never seem to be as good as one would like. Therefore the designer should always consider making a neat job.

Looks and style.
The water cooling systems seem to be just a black box pump, a black radiator and a couple of plastic pipes and metal lumps.
Few systems ever seem to fit well, nor do they take maximum advantage of the various spaces and airflow available in the standard desktop, mini or midi tower case.
It could always work better and look far, far nicer.

Cost.

Many people would assume water-cooling is for overclockers to take their present processors to new temperature levels, or at least to keep overclocked silicon at safe temperatures. But not for all. For me, water-cooling is just good old engineering fun, a chance to develop designs far better than the mundane rubbish available commercially.
As a biker, I see far too many 'customs' built from catalogue parts and too few genuine customs. Even the custom 'build offs' on the TV are a load of second raters, pretty and expensive, but otherwise just more of the same old stuff.
(I prefer to build hubcentre steering recumbent bikes, some are road legal and handle far better then my Ducati. As a mountaineer, I see atrocious camping equipment and poor, bedraggled, overloaded kiddies learning that hiking is all heavy boots and a heavy rucksack. It just ain't so. I walk all parts of Dartmoor, Snowdonia and the Lakes and enjoy it without heavy equipment.)
We can all do better and that includes computer builders too.

The options beyond watercooling.
For some, it would seem ideal to be able to run the processors at just above absolute zero (-273K) but this is unlikely, as strange things happen to sub atomic particles in this region and anyway, the pumps used for getting near this temperature are strange and esoteric. Likewise liquid nitrogen is also a bit of a hassle. Only astronomers need this kind of chip cooling, and then only to reduce sensor 'noise'.
A better solution would be freezing down to minus 20 degrees or lower, but this again is unlikely with present compact refrigeration systems. Keeping the processor at an ice-cold zero Centigrade (32 Fahrenheit) with a compact freezer is more likely in the real world. This is done by using solid state Pettier heat pumps or by using specialist refrigeration liquid such as the successors to 'freon' which can change easily between liquid and gas, so the thermal changes can be used to reduce temperatures well below the normal background (room) temperature. These are the less notorious CFC's the chloro-fluro-carbons. See later.

Tip: If playing with peltier, it is probably best to use the peltier to cool the water of a system, to run it close to zero using antifreeze, rather than use it directly on the processor. The feedback control of a peltier direct on the CPU would need a very fast control system, whereas a peltier working indirectly via water-cooling will give a far greater degree of flexibility and reliability to the system. More importantly, it would allow the processor to reach a stabilised temperature, then stay there with minimal changes in temperature to reduce stress on the silicon and of course, also have a far longer safety and more gradual temperature rise should the peltier or its control system fail.

For most people, aiming for room temperatures using water is easily possible.
The plot improves with AMD and ATI processors which do not get stupidly hot. For some intel processors and the latest batch of nvidia, (if rumours are to be believed), then cooling is needed just to stay in the game. Many overclockers prefer Far Cry and therefore choose to be in the ATI clan, rather than the Doom3 and therefore nvidia gang. Whichever path you prefer, water-cooling for overclocking can go a lot further with cooler running processors, even if only used to improve reliability of an overclocked device.

Whatever you use water-cooling for, it must be sensible and applicable.
Perhaps you indeed prefer hot running processors of up to 100 watts and graphics cards which need two molex connectors to generate frightening amounts of heat. In such cases, water-cooling may be simply necessary to protect your investments, rather than as an aid to pushing the limits.

Before choosing water-cooling, it's always best to check the standard computer running temperature. Pencils rool. Write the temp on the front of the casing for later reference and as a bottom line. It's all to easy to forget the original temperature when thinking of many other aspects of the design. I may find only a five degree drop in running temperature on some after market systems and if so, I would soon be modifying the water-cooling kit, and how it is used.

Considering the water-cooling kit.

There are two main types of water-cooling systems.
The most common is the small bore systems, which need higher pressures to overcome the resistance in the systems. These are more prone to leaks but are generally neater due to the small pipes.
Personally, I don't like small bore systems as their connections are often too constrictive, but they can work well if you get the system nicely balanced. Their advantage is that they can use low volume pumps used for small garden water features, or so the catalogues would have us believe. I believe that even smaller pumps are possible yet still run with reasonable pipe bores.
The other is the low pressure systems, which use larger bore pipes and as such do not suffer from resistance in the system. These are less prone to leakage as the pressures are reduced. The large bore system needs slightly larger radiator piping, but this gives the opportunity for greater cooling.
I also use large bore systems in a special, pump free design as mentioned later.

The high pressure systems can be more compact in its plumbing, but their radiators must still be able to transfer the heat, so radiator size will still remain essentially the same for both low and high pressure systems.
In reality, the use of a less constrictive system is always preferred, but that does not demand large, low pressure pumps. What it does include is the ability to use much better, larger radiators in small systems.
Getting the heat away from the radiator is the weak link, whether the coolant is high or low pressure, with high or low flow rates.
The main point of any system is two stage: To pass cool water over the hot spots and cool the unit by absorbing the heat thus raising the temperature of the coolant, then transport the heat away. Then cool the hot coolant and return it to the system.
Both high or low pressure systems can transport the same amount of heat into the coolant over the processor heat sinks, then through the radiator, with catalogues often quoting flow rates around 20 to 60 litres per minute. I consider this unnecessarily high.

There is a fundamental thermodynamic problem with water-cooling.
As alluded to above, all factors being normal with room temperature and constant volume caused by normal atmospheric pressure, then the cooling temperature across the radiator is the limiting factor. No coolant will reach the same temperature of the cooling airflow, for there will always be inefficiency. Worse still, as the coolant is brought down near to room temperature, then the difference between coolant and the air is so slight that little heat transfer is possible. Therefore getting the maximum temperature difference across the radiator by using cooler air, will need the area to be carefully checked to get the lowest possible running temperatures.
Your water-cooled CPU is not going to get cooler than room temperature. (Unless using phase change, such as water surface evaporation and other esoteric techniques.)

The next point is to make sure the CPU gets the coolest coolant, so ideally takes the coolant from a radiator at the bottom of a case of a well designed system straight to the CPU. Therefore it can be seen that the radiator is the main area of importance to get the lowest CPU temperature. The coolest air in the room is usually at floor level, as hot air rises. If looking to drop a few degrees more than anyone else, then by making the coolant those few extra degrees lower will hopefully help to get the CPU a degree or so lower. If you live in a centrally heated house, tough luck.

If, like many of us poor Brits, and making your system from bits and pieces, then always invest in a decent pump, although modifying or making your own is easy and cheap. You may suffer with a poor radiator, but you must have a totally reliable pump. (Apart from one exception without a pump, as discussed later.)

Pumps have evolved greatly in the last year or so and although the best commercially available are still the same models as used in garden ponds for the last few decades, the better models are now becoming available in computer water-cooling kits. You can always simply pop down to your local garden centre, or read on.

The latest pumps have variable speed settings. You can always modify them yourself or make your own or get new pumps for less than 6 six quid, or for free. An average pump for a computer will pump something in the region of twenty litres a minute or more, but it is how reliably and how efficiently the heat is transported into and out of the coolant medium that is important. For overclocking very hot processors and GPU's, then look for a larger flow pump and larger bore piping. If it has a higher flow rate but a small bore pipe, then you must have higher pressure and this may cause unnecessary problems.
Pumps with variable speeds and flow rates for pennies are discussed in detail later.

The most worrying parts of some systems I have seen is simple things; like not getting air out of the CPU header. Also ensuring no potential bubbles build up in the radiator and perhaps a lack of reservoir.
Very poor radiator design, positioning, use and equally bad fan or radiator airflow is common. Commercial watercooling systems often have all these problems. So what is also desperately needed, is a simple means for getting the system installed, which should be easier than that seen on some systems. Convenience and neatness is still a major problem.

Radiators.

Types of radiators.
There are cross flow, where the coolant goes from one side to the other, or from top to bottom. Also possible is the snake piped radiators, where the coolant flows through a series of S bends through the finning. Either is applicable, but for compact systems the U bend, and for larger systems, the easier one-way cross flow is often used.

Other forms of radiator are discussed later. If you think radiators are boring then you have lots to learn.

Various designs of radiators have the inlet and exit on the same side of the matrix by using a segregated header. This causes the coolant to flow in a U, from the inlet, through half the matrix pipes to the other side, then return through the other half of the matrix to the exit header. But where the hot fins of the inlet are connected to the colder exit area, then heat transfer will not be ideal. Where the coolant makes a double pass through the radiator and ensures there are fewer dead areas in the coolant flow, but also increases internal resistance to the coolant flow.
Radiators should be positioned with the exit at the top to remove bubbles, whether the matrix pipes are horizontal or vertical. Horizontally, the outlet would be at the top, with the inlet at the bottom, but is not theoretically perfect, but perfectly good enough for normal use. When the matrix pipes are vertical in such radiators, then both inlet and exit are at the top and will also work and vent perfectly well.
It is obvious that if using snake type of internal flow, then positioning the internal piping such that air can bubble its way up and out of the radiator is going to be a good idea. Positioning a radiator so that it captures many bubbles is very dangerous, yet I've seen many computers with radiators positioned to trap bubbles and reduce their efficiency.
It is not rocket science to do the job properly.

Without a pump, hotter water in a standard radiator rises to the top of the radiator, with the coolest flowing to the bottom. This is not very important in small systems, as the coolant flow rarely makes much difference in heat between top and bottom, but it may help.
The varying needs cause a conflict of needs between efficiency, neatness and accumulation of bubbles, so in most cases, simply have the outlet at the top or a transparent connection at the top for recognising any build up of bubbles, then be able to eliminate them.

Warning: Any system with both pipes on the base of the radiator will make the whole radiator a potential bubble trap and effectively ruin its capability to transfer heat should bubbles accumulate. As radiators are not transparent, then this is a constant, serious and hidden danger.
Therefore always have at least one upper pipe connection. If you must have both pipes at the bottom of the radiator, then I recommend you solder or epoxy a small brass pipe to the top of the radiator header and fit a clear vent pipe. If the system is sealed, then the pipe can also be sealed after purging the system, but at least a long, transparent pipe with indicator float will show if bubbles are accumulating.
The upper radiator main pipe can often be the inlet, which will allow any bubbles to be seen, but only when the system is shut down and the coolant flow is stopped. When shut down, any bubbles will accumulate and be seen before the system becomes too inefficient.
The CPU header is often the highest point in sealed systems, so bubbles will primarily accumulate here if the coolant flow is poor, but hidden bubbles in the radiator are also dangerous.
Be ye warned; any system may work perfectly well for the first week, but a poorly designed system could gradually become dangerous as you get complacent.
No matter what radiator I use, and I use many, it always gets positioned in the case with great care. No air gets trapped, and the airflow is unobstructed and cool. The exit airflow must also be free too.
If the fan or pump is mounted in the radiator, then ensure the radiator is secure, but free from vibration, possibly foam mounted, or using rubber grommets on the mounting screws.
Where the fan or pump is separate and ducted, then the radiator can be fixed in the case.

In most cases, the radiator is often to the bottom front or rear of the computer case, to be able to take advantage of the coolest air flow. Never allow the radiator to use recirculated air in the case, as this is a waste of effort. A little cardboard ducting on the upstream airflow to the case entry will help reduce coolant temperatures. In some cases, the radiator airflow can be kept separate from the rest of the computer. Far too many computers have atrocious radiator placements.
It is often preferable to have both radiator pipes curving neatly away from the motherboard side of the case, to allow plenty of room for the drive cables. With both inlet and exit pipes to the rear of the case, the matrix would often be horizontal. Where there is plenty of room in side the case, such as a midi tower case, then the matrix can be vertical or horizontal, with both pipes at the top.

To repeat: No radiator should be mounted with both pipes at the bottom. If you demand that both pipes are at the base, then epoxy or solder a small vent pipe to the upper water jacket of the radiator, with a pipe leading to a header tank or vent pipe.

CPU header.

For greatest efficiency, the coolest coolant should ideally enter the CPU header centrally, so the coolant is spread with the highest difference in temperatures for maximum heat transfer. In reality, the system will settle down to a happy heat regime across the system, with little need to get the last few hundredths of a degree out of the system.
It is not just the central flow which may be important, but also the surface area in contact. To get the maximum heat transfer, the base of the CPU header should be lapped to a fine finish, then heat transfer paste used.
To get maximum coolant area for heat transfer, the coolant should be passed over an internally finned CPU header base, so maximum surface area and flow can extract the heat as fast as possible. In reality, this is not needed, as most systems settle down to a working temperature, and such refinements make minor differences to the actual running temperatures, but it all helps towards making a more refined design.

Good exit flow is important, especially to expel air bubbles, but the actual internal flow is a compromise if the header is simply a hollow casing.
As will be mentioned later, making your own header is not very difficult. In the most expensive case, having a silversmith build you a special header is possible. This also allows for a finned coolant area over the CPU, so the maximum area for heat transfer is possible, but can only remove the heat that the radiator can remove. The excellent heat transfer properties of a well designed silver interface may help protect the investment of an expensive processor and to be able to overclock to the max, but a good radiator is imperative. (I design and have such silver items made to special order.) See other options later.

As many people cannot afford silver for the CPU header, then a solid block of copper with a soldered brass water jacket can be built for a few quid and an hours work. If a transparent cover is needed, then a sheet of thick acrylic or polycarbonate can be bonded then screwed into place, or a sheet of glass can be bonded and clamped to the water jacket. I prefer to rely on the clear piping for bubble recognition unless a complex header is used. More later.

Bubbles may accumulate at the top of the CPU header or high point in the system and these must be eliminated. This picture of a commercial design is utter crap, with bubbles even in the CPU header. What a waste of money. Therefore the coolant flow must be such that the CPU header outlet pipe is at the top. Ideally this would be designed to encourage any small bubbles to leave this important part of the system. The preference for a transparent CPU header casing is not just for looks, but as a visual check that all is well. The positioning of the commercially available design opposite leaves a lot to be desired.
Making your own CPU header is described later.

Pump.

Never place a pump high in the system. There is no theoretical reason why the pump cannot be mounted high in the system, then used to continually eliminate bubbles by placing the pump in a reservoir such as a plastic food box to solve some problems but it also causes some problems. In practice, unless you have shaft leaks, then place the pump low in the system, preferably with a header tank, so that any bubbles can work their way up and out of the system and kept away from the pump.

Warning: NEVER fit a sealed coolant system with pump at the top, because the pump vanes could become filled with air bubbles and thus not be able to pump any coolant.
In a sealed system, always fit the pump at the base, so that all available coolant in a leaky system will flow to the bottom and at least get pumped around, even though much of the upper system may have air in it; what coolant is left will still get pumped around and help protect the processors.

A cheap and effective primary test:

Build or buy just the CPU header and fit in into the computer with very long inlet and exit pipes.
Take the computer to kitchen sink or the garden shed, then make up a header tank for the system such as a water tank or bucket on the top of the typical midi tower computer case, and allow it to flow water through your system. Just two pipes from the CPU header, and suck the bottom to allow the water to flow down into the sink. You will have to fit the CPU cooler fan to the motherboards to ensure the Bios reads that there is a fan present.

A simple clamp restrictor on the bottom tube will suffice to reduce the flow. Completely clamping at the bottom retains coolant in the whole system. Relax the clamp to give approximately 5 litre (one UK gallon) per minute flow.
You can use a small bowl and sucking the bottom pipe to syphon the water to start it flowing, then using a jug to top up the upper reservoir is quite adequate.

When a steady flow, fire up the computer and allow it to settle down while running your hottest game. Measure a set amount of water over one minute, and measure the temperature compared to that of the incoming water flow.
The bios screen will show the CPU temperature and allow a comparison with normal running temps.

Get a reasonable flow rate, run the computer and measure the output flow when running a hot game. Allow it to stabilise and measure the heat output of the water with a thermometer. Then compare the inlet and exit temperatures and the flow per minute. The water will be cooler than you will get from a sealed system, as the water is colder from the tap if this is used, but the heat difference is important.
During the test, you can reduce the flow rate by constricting the pipe while keeping an eye on the CPU temperature.

Now carefully stop the flow and when the restriction is such that the CPU temperature begins to climb, then release slightly to get the ideal working temperature with the minimum flow. Measure the restricted flow rate by timing into a measuring jug. You may be pleasantly surprised just how small a coolant flow is needed.
This is with cold water. If the ideal CPU running temp is 35 degrees, then add hot water to the bucket to bring the water to 30 degrees. Now run the test again and see how much coolant is needed to maintain the CPU at 35 degrees. Again, wait until the CPU reaches 35 degrees then slowly release the restrictor to get a stabilised coolant flow at a constant 30 degree CPU. This should not need much coolant flow to stablise.
You now have a very good working reference for your choice of CPU header - the flow rate and working coolant temperature. By using warm water close to the CPU temp, then this is a worst case scenario and thus the actual system may run much cooler.

This is the best way to prove that you only need a small pump flow. You may want to throttle the flow by partial clamping at the base of the pipe work using a clothes peg or other simple clamp or partial plug.
You may wish to further restrict the flow until the CPU runs at a happy temperature, then see how much flow is actually needed. I was happy with less than 1 litre per minute. If you have an intel, then you may need a higher flow rate.

After the test, you can tell from the computer running temperature the optimum and minimum flow for a decent CPU temperature.
Although the tap water is probably cooler than the room temperature, the difference between inlet and exit flow will give you a good idea of the difference in temperature across this system and at the various measured flow rates.

Running temperature:
If the inlet temperature is 30 degrees and the exit temp is 32 degrees, then you have the possibility of having a system capable of running at 2 degrees above normal room temperature.
In practice, the inlet water would run slightly hotter in a normal, closed cooling system, so the actual temperature would be more then the 2 degrees above room temperature. It may be four degrees above room temperature, due to the computer settling down with slightly warmer coolant. But the difference in temperature from this basic test will give a good idea of the working temperature to be expected from the system.
If you used a jug to refill the upper tank from the warmer bottom on, then you have essentially made a closed coolant loop and your readings will be closer that to be expected in a fully enclosed system.

When testing this way, by restricting the flow rate until the CPU temperature begins to rise, you will also have measured the minimal flow rate needed for the system and also found an optimum flow rate, where any extra coolant flow does not lower the CPU temperature.

During the test, adjust the flow rate by measuring the temperature rise of the water as a guide as to whether you need to go for a bigger coolant flow pump or not.
Never use tap pressure, but a head (pressure) equal to the height of a typical small garden pump - then the flow through the CPU header and any radiator will give the true resistance of the system.

You should now have an expected temperature rise for the optimum flow rate. From this you can decide if water cooling is worth the effort.
You can now decide if you need to return to the garden centre for a pump, or brave enough to go to the car parts department to try modifying a new, six quid screen washer pump capable of just 1 litre per minute.

Plumbing.

Remember that this game is to remove the greatest amount of heat. Although the differences in pump position may only be a degree or so between the various configurations, it is up to the builder to decide what is required: Generally, the parts are mounted in the case first, and only then are the prettiest or neatest pipe routes decided, - but just swapping a couple of pipes can make a safer system.

In practice, the plastic pipes do not bend too easily, especially when cold during assembly, so it is best to assemble parts of the system with their pipes, such as the CPU so that the builder can see where the pipes can easily fit and what sort of bends and lengths are best for the system.

I always fit the pipes to my CPU header, with the exit pipe high to allow bubbles to be removed, then see where the pipes want to lie inside the case. Then I choose the best position for the pump, without undue force on the CPU header from tight bends in the pipes. In most situations, the easiest and safest is to position the pump low in the case. The layout of the typical system is such that the CPU is usually the highest point, with the radiator and pump on the bottom of the case, for easy mounting and to keep most of the system cool and away from the electrics.

Wherever the system is at a slightly lower pressure, bubbles can creep in from low pressure zones, such as minor suction from poorly fitting connections, or a worn pump seal. The pipe seals can be cured with a smear of silicone sealant, but pump seals demand a new pump, a new seal (or two) or preferably a pump of better quality, or as a desperate measure - to submerge the pump underwater. See later.

If any pressure leak (outwards) is likely to occur, it would be in the higher pressure areas first.
If any bubbles occur (inwards) they would enter in the low pressure zones.
It is for this reason that I ensure the driveshaft seal is on the low pressure side of my designs of pump, and that there is a bubble removal design of plumbing in my systems. This 'belt and braces' approach eliminates any bubble problems that may occur and also reduces any potential for leaks in the coolant.
I far prefer bubbles to enter the system, then be purged, rather than for any coolant to leak out. Luckily, in a truly sealed system, the volume of coolant will not allow much air to enter, especially when it gets warm and expands slightly pressurising the system by flexing the warm pipes.

Making and setting up the system.
The pump can be fitted on the base of the machine, but if feeling less than confident, can also be mounted in a small plastic drip tray.
Always dry fit the CPU header to see which of the various ways around it will fit.
Always have the CPU header exit pipe in the highest position to remove any bubbles. To optimise the cooling, I always mount my motherboards upside down, BTX style, but I build my own cases from scratch, so that my systems are as good as possible.

Getting cooler air across the radiator is a primary part of the exercise. Even a few pieces of corn flakes packet and sticky tape will help towards cooler airflow. If you live in a centrally heated house with double glazing, then tough luck. The radiator is usually easily fitted near the base, but never allow dust to accumulate if in a dusty room, especially if the case is positioned on the floor.
Where the radiator is not mounted close to the case entry, then always duct the radiator to the outside, to prevent using recirculating warmer air in the case.
Ideally, the coolest airflow would be from near an outside house vent from a sheltered part of the house, but this is probably not worth the effort unless living in Finland and wanting sub-zero air across the radiator, and of course, you use antifreeze and that there is no chance from ice, snow or real lemmings from entering the ducting.
If your computer is to be a permanent fixture, then running a couple of small pipes through a wall or window frame to allow the radiator to be mounted outside in the shade and breeze may be applicable, but never induce too much restriction in the coolant flow. Make sure the warm and cool pipes are insulated from each other, even if only by a piece of cardboard.

Water boxes.
Completely submerging some types of pump in coolant is not needed unless demanding total protection or suffering from poor shaft seals. Making your own submerged pumps is easy as it allows any motor to be used and a simple shaft to a basic, submerged pump body, with the motor above the water level. See later.
If submerging or partially submerging the pump then consider using a 'Tupperware'(tm) style of food container and always fit the waterproof lid. A couple of rubber grommets from a car shop will seal the inlet and outlet pipes if they are through the lid or through the higher sides of the box.
Making an air hole, small bore vent pipe and filter will greatly reduce bacterial contamination of such 'open' systems. An air vent filter is easily made from a length of small length of pipe and inserting a piece of cotton wool. Adding some bath sponge prevents sloshing. Cutting the foam with a harder upper mounting flange of plastic glued in place, makes for a splash skirt and makes for a quieter system which mounts the motor free of vibration.

If wanting to eliminate bacterial ingress, use distilled water, or boil the coolant first for five minutes to destroy all bugs, or add one water purifying tablet to kill off any nasty bugs. Preferably soak any cotton vent in an antibacterial liquid, as used for wiping kitchen work surfaces. If carrying the machine around, then use open cell bathroom sponge as part of any reservoir to prevent sloshing, as this is so much neater than anti slosh baffles and far quieter too. If air contamination is common, then simply float a film of polypropylene on the surface of the coolant. (Polypropylene floats.)

Dummy runs.
Just like fixing hard drive cables, always make dummy runs and get the pipes perfectly aligned. Always try to eliminate any potential high points where bubbles may be trapped. Once the whole piping is sorted, then build the system dry, assembled into the computer to check the fitting and the run of the pipes. As most pipes are soft plastic, never allow them to rub against any abrasive areas, especially the sharp edges of some cheaper cases.
When cutting the plastic pipes, use a sharp knife and try not to squash the tube nor distort it, so it makes a neat fit into some of the cheaper connectors.
When satisfied, remove from the computer and fill the system. Run the system for a couple of hours away from the computer, using a 5 volt or 12 volt supply or whatever is required. If the pump is not supplied with its own transformer, then an old computer power supply will do nicely, or a 12 volt car or bike battery charger if appropriate. Details of building variable controls are mentioned later.

While running, use this time to improve the system. Move the components around to remove any potential bubbles or to get them to a high point were they can be removed by pouring in more coolant. While testing, the pump and radiator can be mounted on the table using blue tack or plasticiene, with the CPU header held for a while in its relevant position with a piece of string to check for any air entrapment problems.

Don't just test the cooling system, check the power supply if a transformer is used to power the pump motor. Many cheap power supplies fail due to overheating. I always open the casings, then carefully add air vent holes to help keep the transformers from cooking.
Remember that you are building a long and involved way to protect the CPU. A chain is only as good as it weakest link. Make all links as reliable as possible.
Bomb-proof is your lowest acceptable standard.

Removing any air bubbles is done by simply making the outlet of each component at the highest point and looking through the clear piping. Eventually all the bubbles will be in one convenient place, when the pipe carefully opened and topped up to remove all traces of air. If you are having lots of problems, then the final purging could be done under water, but this is rarely necessary.

If using a high pressure system without self sealing connections or a poor design, then sometimes it may be preferable to wire the pipes in place, although small hose clips are also possible. These clips are available in metal or plastic. If using tie-wraps, always use two on each connection, with the joins staggered, as the area directly under the join can make a poor seal.

Fully dry the outside of the system, run for another couple of hours and check for leaks. Use any case modding UV neon's to look for leaks if any coolant additive is UV sensitive.

When confident, install the system using the usual CPU heat transfer paste with any other careful considerations and alignment processes.
If a noisy pump, you may wish to use double sided, sticky foam pads, as used for model aircraft servo fixings or to mount it in foam to isolate it from the case.
In many cases, the radiator fan may be run from the motherboard. In other cases, the radiator fan may take its power from the hard drive Molex connectors, when your radiator fan sensor wire (usually yellow) should be connected to the motherboard to give a shut down warning. Technically speaking, the water pump is essentially the same as the CPU fan, but these rarely have a yellow sense wire for the motherboard CPU fan connection. So use a fan with a yellow sensor wire on the radiator to become the feedback for the FAN1 connection on the motherboard. This is needed, as most motherboards will dislike having no pulse from what it thinks is the CPU cooler.

When satisfied and all is well after two full checks, refit into the computer and run the pump and radiator fan for a while just to be sure, then switch on the computer.
Check that it all looks and sounds well, but be prepared to switch off immediately.

Run the CPU temperature programme, it may be in the BIOS or a separate programme on top of your operating system. Water-cooling systems take a long while to stabilise, so do not take the first temperature as the normal temperature. Preferably run the computer using your most intensive game for half an hour, then check the temperature. It is assumed your BIOS over-temperature warning or shutdown is active. If all is well, then adjust the radiator fan speed to a preferred level for noise vs. heat flow. Allow five minutes for the system to stabilise at the new fan setting.

Where you wish to run your fastest game and cannot check the CPU temperature at the same time, then set the maximum BIOS temperature very low to give you feedback. Alternatively, you can fit a temperature sensor to the CPU header or use an IR thermal sensor. Alternatively shut down the game or reboot into the BIOS for an instant assessment. Remember that BIOS temperature sensors are not so accurate as one would like, but perfectly acceptable for comparative tests.

Now test the temperature limits by running any overclocking settings and your most intensive games, after all this is why you are water cooling. Then reduce the fan speed slowly to get the best compromise. If the pump can be adjusted, then adjust this too. Remember that pumps are far cheaper than CPU's so don't run them at full power as they are often built down to a price. A slower pump motor is usually a more reliable pump motor. It is for this reason I occasionally use custom high-spec racing motors, then de-tune them, or use high quality motors designed for steady, long term running. You may often find that there is little difference in CPU temperature between the motor running at full power and at tick over, - so always check, then always adjust for reliability.

Keep the temperature programme running for the first few days.
Check every hour for any bubble collection denoting a slight leak on the suction side of the system and then daily then weekly. Also check for any coolant loss. Learn to listen for any audible changes in the coolant pump should it begin to fail early.

Finally decide if the whole exercise was worth the effort.

Compare the running temperatures with the one you wrote on the case in pencil before you began. If the cooling is not much different to air cooling, then consider removing or modifying the system.
You may find that your standard commercial system offers little or no advantage over a good air cooler. Do not worry, as the commercial systems can be improved. - Improved to the point where only the power plug remains !

Modding your coolant system.

Many people like to tinker with their computer systems, it's a big toy and lots of fun, and for some, a chance to pose.
Water-cooling is no different.
There are many small or large ways to add to, or improve your basic water cooling system. But improvements are only improvements if you have problems, otherwise they are called unnecessary complexities. The biggest problem or disappointment is spending lots of cash, with little improvement in the cooling. If all works well, then there may be a few minor problems, such as a slight leak, noise or ugliness.

Fitting a header tank or reservoir.
Perhaps your system has a small leak. Make sure you solve the problem and not apply a reservoir tank. Most water-cooling systems are sealed and work perfectly well when all bubbles are removed and do not appear afterwards. In a few cases, bubbles may enter the system, but this is not a problem if they are removed automatically, perhaps using a vent or header tank. Where coolant is being lost, then solve the problem.

A header tank is a passive device containing a higher level of coolant and only acts to prevent coolant loss and to give a small 'head' of slight pressure in the system. If properly designed, will also allow bubbles to move up to the header tank and out of the system.
A reservoir is usually an active part of the system and the coolant in the reservoir is often in the general flow of the coolant. A reservoir is common if using a submerged coolant pump.
In common practice, be it domestic heating or supplying water to a large city, the header tank is also a reservoir.

If building your own system or modding, then perhaps some air bubbles will naturally float to the upper part of the system. As the coolant exits from the CPU header which is often a high part of the system, then it is possible to place a T piece in here and have this going up to a small header tank. This would encourage all bubbles from this high point in the system into the even higher header tank. The higher coolant level will also give a reliable signal of any coolant loss over the years. If you never check these things, but simply make an occasional glance, then mark the level when the machine is warm, so you can check it at any time it's being used.
Note: Due to expansion and contraction of the various components, the true coolant level should always be checked when cool, before the computer is run in the morning, so the relative levels will give true indications of coolant level.
The header pipe will connect to a miniature reservoir which is open to the atmosphere top prevent pressure or vacuum building up in the system, and will thus be at the top of the system to give a 'head' of coolant. As most systems rarely leak, then any loss will be minimal. A simple length of pipe would be more than adequate for a header 'tank', but mainly to act as a high point and thus isolate any bubbles in a problematic system. I often use a small, clear plastic car fuel filter at the top to act as a minor reservoir and also keep out the dirt.

In low pressure systems, a suitable tall header pipe can be on the pressure side, but it is always best to place the header pipe on the suction side of the pump or at least in a low pressure section of the plumbing. Therefore the plumbing could be different if using either a header pipe and reservoir.

Warning: Always fit pipes to open atmosphere in the low pressure side of a plumbing system, never in a high pressure side for obvious reasons. Place your header pipe on the suction side of the water pump, so that, should any system blockage occur, the water will not overflow.
BUT: In some situations where the builder wants INSTANT warning from the coolant, it may be possible to build the system 'wrong'. If the header pipe is placed on the pressure side of the pump, then any blockage after the header pipe, such as in the radiator or CPU header, will cause the coolant to be pumped out of this higher point which is open to the atmosphere. Building this to indicate by splashing over the user, or to fill a water sensing device connected to the computers 'off' button makes for an excellent safety system. If you prefer such an open pipe and it is suitably positioned, this can act as a safety warning device. If such a blockage occurred, then having the header pipe exiting at the front of the case will give an instant alert to imminent failure. The heat reserve in the header coolant should be enough to allow the machine to be shut down within twenty seconds or so. It is always best to let the system warn you, rather than you having to keep a regular eye on it. If you fit an over flow float valve, then this can switch your machine off using a very simple second connection to the ATX power button.
The switch will need to be kept down for four seconds or more, which is not a problem on a float valve, especially if using just a brass contact and a piece of wire to make the contacts. These can also be connected to the power switch wires of an ATX motherboard and all is safe should the coolant get low or spring a leak.
The ATX power switch can be controlled by connecting to two pins to be shorted by a metal object. A closed cell foam ball covered with aluminium cooking foil inside the header pipe, with two pins pushed into the pipe above the level for an overflow and two pins pushed in below the minimal coolant level will give a simple and effective safety system for blockage and coolant loss.

Placing the header pipe just before the pump in a low point in the system, would not eliminate bubbles. Therefore the system will need to have the header pipe at a high point, perhaps just after the CPU header exit. This will ensure the header pipe is in a safe, neutral pressure zone in the system, between CPU header and radiator. Therefore this system would be pump-CPU-radiator, with the header pipe on the neutral pressure area between CPU and radiator on the highest point in the system to remove bubbles and also be on the safe side of the pump.

Any coolant reservoir can be used, but just a simple length of coolant pipe will do, as the coolant loss should be zero or thereabouts. Just because bubbles are entering the system, does not mean that coolant is leaking out. It is this reason I prefer low pressure systems for minimal coolant loss. On a properly built system, only evaporation will cause long term problems and this can be minimised to give extreme longevity.
For a filter, the open end of the pipe can be simply fitted with a cotton wool stopper to prevent evaporation, yet allow atmospheric pressure to prevent an over pressurised system. Another good choice is to use a small, transparent car fuel filter with a paper filter element. If carrying the machine around, then use open cell bathroom sponge as part of the reservoir to prevent sloshing. If air contamination is common, place a film of polypropylene on the surface of the coolant. (Polypropylene floats.)

Visual warnings.

There is nothing to stop the header pipes running outside of the case, or beside the window against a contrasting or zig zag background to allow constant coolant level inspection. This would be particularly good if you mount your ATX motherboard upside down with the CPU and thus the coolant system low in the case, to give a nice, tall header pipe.

For those who do not trust pump motors, a light could be fitted across the wires to the pump, allowing a warning light to be activated if the pump stops turning. Alternatively, a small cheap, digital tachometer could be used and mounted on the front of the case, perhaps beside the motor speed controller. See later. The fan would be monitored by the motherboard in the usual manner. Building in a pulse wire which can interface to the motherboard second fan connection will also offer an extra warning device. This could also be interfaced to a number display, or my preference, a colour bargraph display.
Even a simple cardboard rotating disc pushed onto the end of the shaft with a spiral drawn on it will give a perfectly usable visual warning device.

Neatness is difficult with plastic pipes.
If needing a sharp bend in a pipe, simply and neatly wrap a thick copper or a finer, steel wire around the outside of the pipe and bend to shape. A small welding rod with the flux removed, or a small knitting needle or wire coat hanger is ideal. As bending around the pipe is not recommended, as it can be crushed, always pre wrap the wire using a piece of doweling. Adding a flourish of a tie-wrap loop or a stand off mounting can make for a neater system.
Another way to make neat bends is to slip small plastic angle bends over the pipe to allow neater corners. Alternatively use brass pipes, but making such bends is not easy unless a trumpet or saxophone maker. In such cases, simply make the brass pipe with an open middle section and slide the pipe in place, then bend the centre, with the two sleeve ends holding the pipe. See picture. You may wish to solder on some support brackets before inserting and bending the plastic pipe, to help make a really neat case. This also makes the CPU and GPU headers far easier to position in the case.

At this point the reader should have a system working reasonably well. It may even seem perfect, even if you bought all the most expensive bits from the best catalogues and websites.
But a much nicer systems is most definitely possible.

A truly reliable and basic design.

The simple car system is where there was no water pump. Just a smooth, large bore pipe leading up to the radiator with a decent fan. Because the system was designed for hot water to rise easily and the cold water descend to fill its place, the whole system can be simple and effective, reliable and quiet. Adding a simple large bore radiator and a suitably designed CPU header with one pipe high in the header and the other low, would make a very quiet computer which would only have the one radiator fan and no inherent mechanical problems. Always use a radiator with the pipes vertical and the hot riser entering the top of the radiator.
Surprise, surprise, this will work better if the case has the motherboard upside down, BTX style, with the CPU at the bottom and the simple, single pass radiator mounted high in the case.
Because it works without a pump, you can add some flaky chrome pieces of neutrally buoyant plastic which will highlight and check the coolant flow. Try scraping the back of a toasted CD then with light oil to get the buoyancy right.
If you have a tall case, with your CPU near the bottom with one pipe low and one high in the header, AND it is a large bore system, AND the radiator is a single design where the hot coolant can flow into the top and cool by flowing down though the radiator, - then remove the pump and give this a try. Use just use one fan set low on the radiator. The radiator is placed high and vertically in the case. Insulate the hot pipe to encourage hot water to rise.
It may only take half an hour to get the pipes running smoothly vertical. If it works, and your CPU keeps suitably cool, then you have no need for a pump and have a far more reliable and quiet system. More later.

Coolant additives.

Pretty flowing water.
Many people would like to see if the coolant is actually flowing. This is difficult, as placing plastic balls or other detritus in the coolant for observation is not going to do the pump vanes any good. If an indicator is needed, then fit a length of contrasting plastic thread in the pipe. Place carefully and securely in the system, held by both ends should it break, and placed in a long, straight length of pipe with a simple and non constricting clip. Never cause unnecessary restriction to the coolant flow. A snug fitting plastic sleeve with a piece of nylon sewing thread may suffice for most people who do not trust their pumps or who just want to see the pretty water flowing. A simple loop of nylon thread inserted at the same time as a clear pipe is fitted over the pump outlet would be ideal, plus a splodge of silicone sealant. As the cord will want to stay beside the side of the pipe, always make a knot in the loop, then keep the knot positioned in the middle of the flow, so the cord trailing downstream from the knot will remain in the central flow.

If you want a prettier indicator and your pump is a basic design, such as an old car screen washer unit, (see below) then you can but some glitter glue pens, which have the every fine flakes of glitter which should not clog the pump vanes, then wash the glitter glue and dry it to remove the glue. The flakes can then be added to the coolant and if illumined properly, can give a pretty, dynamic display for checking the coolant flow. As they are heavier than water, then they will sink to the bottom and hopefully re-enter the plumbing from the radiator, but probably best forgotten. I have experimented with them, but finally ended up with simply addling a whole lot of glitter and live with variable levels of flow indication.
In a few cases, directing a safe, 5 volt pocket laser onto the coolant flow will give some interesting effects on reflective glitter when it all works as intended. Using glitter flakes from larger sources may cause radiator or pump blockage. Adding a dye can have some effect on laser light.

If an open system, with the pump submerged in a reservoir, then the return pipe can simply cascade like a small waterfall into the reservoir to indicate that coolant flow is correct and also add a background noise indicator.

If you have a clear side panel, then this could also be the reservoir, where the coolant from the radiator enters at the top and the whole side panel becomes the coolant flow indicator. Making entry and drain holes in such panels is not easy, but plenty of epoxy resin and some car windscreen washer connectors will usually suffice. If building a waterwall (c), then you can add a vane indicator near the radiator exit pipe. See later.

A temporary solution (in more ways than one) to check coolant flow is to mix oil and water together as the coolant, this will separate when not used and if different colours, then will allow the first minute or so of pumping to be seen as flow. Eventually this will be mixed by the pump and may not be discernible until the system has stopped again. This indication is only applicable for the initial few seconds. Making sure the oil and the water are not easily emulsified will depend upon the oil and the design of pump. Try it if you must, but do not expect to be too successful, as heat, oil and water can make something akin to mayonnaise. Best used in waterwalls using thermo syphon.

Pump Circuit choices.

I do not like many power connections leading to the computer, when one will do. Keep it tidy.
If you decide to use a separate power supply for the coolant pump, which is highly recommended, then you may be able to open up the computer's power supply and add a couple of mains wires soldered to the back of the mains socket connection, then feed the wires out with the other PSU cables and add a fuse in this line. This can then be used to power a very reliable, overrated, understressed power supply transformer for the water pump.
I prefer to exit these wires directly from the bottom of the PSU case, through a separate grommet and add some alloy cooking foil around these AC mains wires to reduce frequency problems from any nearby 12 and 5 volt wires.

If the pumps' power supply has the three mains socket pins sticking out the back, then these can be cut off, sealed and the wiring connected internally for safety and a new, smaller mains connector used. This wire keeps the whole system integral in the computer and automatically switches the coolant pump on with the mains to power any specific power supply transformer for the pump. I always disassemble these secondary power supply cases to add some cooling holes, as they often fail due to excessive heat in the transformer case.

If you keep the computer switched on all the time, with just the ATX soft off switch used, then the monitor and motherboard are still alive. - But you may only want the pump to work with the standard, single small computer power switch which is connected to the motherboard on ATX systems. If so, then simply connect the mains power supply for the pump via a 12 volt relay switch for a couple of quid. This can then be operated via one of the hard drive power connectors to trigger the relay, without having the transformer and pump on all the time.

For long term reliability of a pump it can be reduced in power, as running flat-out is not always needed. Unless cooling the GPU and playing Call of Duty, Far Cry or Doom all day, the pump motor could be turned down using a rheostat, such as a ceramic potentiometer which can take the power rating of a small pump motor, or a simpler device such as a switch with a resistor in the line or to switch between the 5 volt and 12 volt rails, or using the switch in any separate power supply transformer. If using a powerful motor, something more than a video motor, then use a potentiometer for a rotary control with a TIP 120 power transistor which can handle up to 60 watts to control the motor, as described later. Reducing the motor power may also reduce noise.

You may notice on some air cooled CPU coolers, that by reducing the airflow, the heat transfer remains just as good, as slower, smoother airflow across the fins works more efficiently. My CPU runs at 42 degrees with the fan at 5,000 rpm and 43 degrees with the fan at 3,000 rpm - far quieter and the fan is probably far more reliable and less likely to collect dust. Likewise with my water-cooling systems, reducing the coolant flow rate may cause a smoother flow over the CPU header, reduce turbulence, slow the speed through the radiator and may thus work just as well. Experiment in this area to assess your system, but always remember that a water cooled system will take much longer to settle down to its working temperature than for an air cooled system.

If you decide on a separate power supply for the pump, then it may end up with one pair of insulated wires connected to the 240 volt wire from the PSU, with an internal fuse of about 1 amp rating. Another two wires leading to the HDD Molex connector with a micro relay integrated inside the case, and a third pair of wires leading to the potentiometer or Tip120 controller to adjust the motor speed. This is not exactly difficult, yet many commercial systems have just the motor connected to the HDD connector and can thus cause many problems if the motor fails or causes electrical noise in the power supply to the electronics, so always choose a safe way to power the pump. More later.

Building CPU and GPU headers.

So let's go a little further than just the CPU, as the costs of making a GPU water cooler when compared to buying the graphics card will be mere pennies.
GPU (Graphics processor unit) coolers are fraught with problems, as the memory is often superfast, overclocked and needs cooling too. Therefore it is probably not a good idea to water-cool the GPU unless considering the onboard memory too.

It's no one's fault, but for water-cooling, the graphics card is upside down on a midi tower. This is because of the superb backward compatibility back to the original PC, 1 MHz 8088 chip, when ye ancient legend hath it, cooling wast nay a problem.

All my custom built cases have standard ATX motherboards upside down to help CPU and GPU cooling, not unlike BTX, but far, far cheaper. It makes GPU cooling much safer. Build your own, it's very easy. See my companion monograph on the same website.

If wanting to cool a very expensive graphics processor and its memory, then always consider turning the motherboard upside down or desktop style, to help remove bubbles from near the chips. If lucky then you may only need to turn your ATX 'beige box' upside down into a pseudo BTX style, and still have it work perfectly well, albeit with a few minor adjustments.

Consider a second water cooling system so that if one system fails, you have not lost both your CPU and graphics card. It costs a lot to replace a CPU, but can be survived with a few tears. Having to replace both CPU and GPU may cause mental meltdown and chronic wallet failure. Using dual pumps also takes the load off a single system pump and makes life far easier for all items, while also increasing coolant flow due to far less restriction in the systems. Separate systems allow cooler coolant to both CPU and the GPU, rather than coolant first to the CPU, then warmer coolant to the GPU. It also allows a blue dye for CPU and a red dye system for GPU. After all, this may not be hidden.
If using just one system, then buy a system with a large bore and coolant flow, as any restriction in one part of the system is a restriction to the whole system.

Build your own CPU and GPU headers.
Please note: When disassembling the heat sinks from the graphics card, always make sure they can be replaced. Always be very careful with the small plastic retainers. As to serious overclocking and reviving pipelines, look to the wwweb for specific details on your GPU. Powerstrip is a good beginners overclocking tool.

WARNING: The heat sink compound may contain silver and when wiped off, this can short circuit the memory and GPU pins. So always clean off any heat sink compound INWARDS, towards the centre of the chips. I use a piece of card to protect any pins.
Although the latest memory chips are surface soldered and do not show pins, the heat compound can still work its way into this hidden area, so be careful. If in doubt, clean any remaining compound scrupulously with a safe solvent and a small, stiff, non plastic brush. Always make a note of the code numbers on the memory chips, especially the last letters, as this can tell you if they are the faster types, likewise the GPU codes.

If the GPU and memory are perfectly level in their upper faces, then simply cutting a large copper sheet to cover them will suffice. To check, put a little heat transfer paste, butter or grease on the GPU and memory chips, then place a sheet of plate glass over them. If you don't have this, then an old CD clear case cover. If the memory and GPU are all at the same level, the pattern of displaced grease will show a perfectly level pattern on all the items. It is important to put central pressure over the GPU to make sure this is the centrally level item.
If they are not all the same level, then you will not be able to build a single graphics card water-cooling jacket for GPU and memory, and separate items will have to be made.
If the differences are minor, then perhaps some aluminium or copper shims may be made to build up the height of the memory chips to the level of the GPU silicon die. Such shims are possible by measuring the difference in thickness between memory and GPU, using a set of feeler gauges, available from any car shop for a quid. Perhaps some carefully flattened and polished cola can could be used for thin shim, or look elsewhere for thicker shim. As the typical alloy beer or cola can is cold drawn to shape, it has inherent springiness, so keep it large, clean then mark with soap, then heat over a gas flame, until the soap turns brown, then plunge into cold water to make it malleable and easier to fit.
Never use more than one shim, so that the heat transfer path is as perfect as possible from the memory to the graphics cooler base. Make the shims then always double check using the grease and glass method. There may be a little room for alignment from the flexibility in the graphics printed circuit board, but only by a couple of thousandths of an inch, and only if decent clamps are used.
At a push, it may be possible to slot the copper so the sections over the memory can be slightly cranked to give perfect fitment, but this takes a long time to get perfect.
If in ANY doubt, then simply make separate coolers for the GPU and memory. Don't forget to check for memory on the reverse side of the graphics card.

A large copper sheet to cover it all will need a cardboard template, about 1/4 inch thick to absorb the heat and so it does not distort. (5mm thick.) Then off to your local stockist. If no copper, then aluminium will do quite nicely, especially if your system is being carried around. I always ask if I can rummage around the scrap bins, then buy anything likely for pennies.

I employ two ways to make GPU headers, the solid block and the built up version. Both work equally well, as they both have the same heat path. the solid block is better, as it gives a larger heat sink, should the system fail, but takes more engineering skill, and of course a big chunk of alloy. For those who only have access to a moderately thin sheets of alloy or copper, then a built up, sandwich version is also described later, but needing less engineering skill.

A large, square block of copper or aluminium will need to have the coolant channels added. This is best done by marking out on the sheet where you want your coolant to flow. Ideally, the coolant will enter centrally over the centre of the GPU, then flow outwards, evenly to the memory. Therefore marking out the positions will allow a well designed water casing to be built over the copper sheet.
Most graphics cards have a selection of holes perforating the printed circuit board. Look for those equally spaced over the memory chips and consider if this can be used to evenly clamp the coolers on the memory on both sides of the card, so look for a pair of equally opposing holes across the GPU for clamping the main cooler. Even a thin bar of piano wire will be strong enough to clamp them together using a spring and clamping sleeve on the wire to maintain clamping pressure.
Now make a full size sketch of the proposed coolers. Decide where the mountings and where any coolant and air entrapment problems may occur. First drill the main mounting holes to correspond with the graphics card mounting holes. Then lightly mark out the GPU and memory positions. Also ensure suitable clearance for the various components such as capacitors.

Where there are dead spots in the metal block, there is room for threaded holes for studs or screws into the heat sink sheet, and these will allow a sandwich of plastic to be clamped over the heat sink sheet. If you cannot tap a thread, then use countersunk screws protruding from below the heat sink sheet. These must be flush and not cause mounting problems. At least four, preferably six studs will ensure the water jacket sandwich will be secure.
To cheaply tap a thread, use a steel screw, then taper the ends and cut a hacksaw slot, lengthways along two sides, to make an improvised tap. This will suffice for soft metals such as copper or aluminium if done slowly and carefully.

Ideally, a thick slab of alloy would be used to carve out the water channels. Do not use plastic which may soften under heat, such as the lower melting point thermo plastics, if you must, then use thermo setting plastics.
As a thick sheet of plastic is not available for a water jacket, then it is easier to build up a sandwich jacket using 'plastic metal in a tube', available from most DIY and car shops. This can be built up around a cardboard former, with cling film over the copper sheet so it can be easily removed. This allows the mould to be tidied up prior to assembly. If preferring to bond to the copper or alloy, then simply bond it in place after roughing up the surface and scrupulous cleaning. During this process, the brass or plastic pipes must be inserted for best coolant flow and any smaller air vents included.
If keen on soldering, then the jacket could be made in brass or copper sheet. Use a high temperature plumbers solder if possible.
If wanting to view the coolant flow, then a flange can be moulded into the plastic metal, or soldered to the brass walls to allow a glass sheet to be siliconed in place and then clamped. A transparent cover is highly recommended, if only to check that all is well.

Here is a basic diagram of a one piece GPU cooler, using a copper sheet and plastic metal in a tube walls with glass cover. The ones I build are not quite so neat, so a pretty picture is preferred. The middle section is just some car body filler, used to easily mould the water channels. If you have one plate over the GPU and another over the memory, then just build it with an interconnecting brass tubes for convenience.
Note: I have gone one step further and now mould the water jacket directly into the CPU and memory chips, using brass interconnecting tubes. But this is committing an expensive graphics card to a terrible fate if it does not work as expected.

Ideally the inlet will be directly over the GPU, or if room is tight or using a glass cover, then from above as shown with the black lines. Then the coolant flows around to the outlet at the top, above the mid point between the memory banks. Making internal baffles or coolant routes will ensure the coolant flows past the GPU area, then across each memory bank in turn.
Always make sure the coolant flows in a single path. In this case, into the centre, directly over the GPU, then up to the right, down to the first memory bank, then exiting after the second, upper memory bank. Making two exit paths from the GPU, over two separate memory paths can allow one to flow easier than the other. It may make little difference in practice, but the chance for reduced flow in one channel will be the one that limits the overclocking potential.

Warning: Always remember that most graphics cards are positioned in mini towers, with the GPU on the LOWER side of the graphics card printed circuit board, so the bubbles will always want to be beside the hot spot in the heatsink and this is very dangerous. Never allow air bubbles to reside near the GPU or memory areas. This is the reason I now always mount my motherboards upside down on my home made custom cases, not dissimilar to BTX format and for better cooling of all components. Having the CPU low, the pump low and the radiator low, obviously makes for less piping, less head for the water to be pumped up to and a lot tidier. For more details, see my website on designing and building your own computer cases.

If the inlet pipe was to enter the GPU cooler from above, as shown with the black line, through the side wall, rather than the glass cover, then it could be positioned with its internal end lower in the casing, to give full flow though the GPU area, and also make for neater external plumbing. As the pipe would block the flow, the pipe would enter to the left in the picture. Another alternative would be to perforate, or slot the end of the pipe to more effectively direct the entering coolant over the GPU area. Just use your imagination for the many possibilities.
As plumbing is awkward, always have the pipes to and from the graphics card easy to mount and plumb in position. Also make them securely mounted to prevent unwanted distortion on the chips, form strained external piping. This will require making small brackets to restrain the pipes on the graphics card, and must always be done very carefully to prevent GPU track damage, yet maintain secure entry and exit piping. I find this the hardest part, so always make sure you can build up a nice soldered bracket for the pipes to and from the graphics card.

If you allow the coolant to flow in two directions to the outlet pipe, such as splitting the flow from the GPU to each memory bank, then this is asking for trouble, as there will always be an easier and a harder way through and one bank of memory may run warmer. If large differences in flow, then you can only overclock to the warmer running memory. You could simply make one big water area and cool all at once, but as the GPU is the hottest, then being able to put the coolest coolant straight over the 'hot spot' will help reduce the GPU temperature a little more.
You will also see in this example, I have included a small vent slot in the top of the GPU area, to allow any bubbles to vent up, out of the system. This may not be needed, as most GPU's are mounted horizontally in a mini tower case. In a desktop or micro system, it is a vitally worthwhile consideration should the graphics card be used in such positions where the unit is mounted vertically. The point to note here, is to know your system first, then eliminate or prevent problems before they arise.

Once the walls of the sandwich are made, a final layer is added and while still drying, the upper plastic or glass sheet is added with a piece of cling film to give a perfectly flat sealing joint face and also show up any thin areas.
Then the central part is bonded to the copper sheet with silicone sealant, in the same way as fishtanks, then the upper cover or clear plastic sheet added. If using a glass cover, then an alloy strap or plate is used to keep the glass in place, or a series of spring loaded edge clips, for which you will have decided the overall thickness beforehand, or simply remove the glass and file down or build up the thickness to suit. If plastic, then this can be drilled for the screws from the copper or alloy base to align with holes drilled though the upper cover. Minimal retaining forces are another advantage of a low pressure system.

When all is correct, then the cooler can be tested before actual use in the computer and pressure tested by plugging one hole and using a long length of pipe about eight feet to give an eight foot head of water to pressure test the device. Hang it out the window or hang the top of the pipe from the ceiling, then allow to stand for an hour to check for leaks.
I check my systems by submerging in a bowl of water and then blowing into it to look for air bubbles which are a more reliable check of any leakage.
If all works well, then it can be lapped prior to use and assembled onto the graphics card, using thermal transfer paste and careful tightening down. If all has been done well, there will be no distortion and the heat transfer from GPU and memory will be perfect. When replaced in the computer, it should be tested over many hours and checked for leaks, as the heat and poor mounting may cause some distortion.
Most graphics cards are mounted horizontally, with the best bits on the bottom. Viewing the coolant flow through the graphics card header is difficult, so a small plastic mirror placed at an angle underneath will help check the system is working properly and add an extra feature to the 'modded' machine. Including a white LED will also help. In a few expensive designs, you may have to replace the fan, to fool the graphics card or drivers that it is being cooled.

A single large GPU cooler makes for a neat design, but is often not possible.
The height of the various chips or a rouge capacitor is always a common problem. It is possible to buy an identical capacitor for pennies, - look for the capacity in microfarads, and the working voltage, - then solder on the new capacitor, but use longer legs to reposition it to clear the cooler, and sleeve the legs with plastic tubes from domestic or car wiring.

Therefore, three cooler units, one for the GPU and two for the memory units may be needed. This is very difficult and takes an awful amount of hard work, but is removable, should it not work as intended. This is engineering and most people will simply not want to play this game, so easier options are mentioned later. On standard cases with the graphics card in the poor position, I prefer this system, as it give the best cooling, with minimal bubble entrapment. Only on BTX format do I use other cooling systems. It is often easier to build your own BTX format case than do the following.
The trick of course, is to make a drawing of the GPU and memory layout, draw in the blocks, then decide the coolant flow to eliminate any bubbles, then ensure they all connect up easily without any excessive piping. Then decide the best placing for the pipes from the card to your radiator and pump. This is not so easy, especially if the graphics card is mounted vertically as in a micro system or desktop. In a mini tower, the graphics card is often horizontal, so the bubbles will probably work their way out. But never assume the bubbles will all leave happily. See the picture of all three items, below.

For simpler cooler units, just use a thick slab of aluminium (or if rich, copper) and drill holes for the inlet and exit pipes, which can be a tight push fit brass tube.
There are many forms of drilled metal slug. The simplest is a single hole - In one end and out the opposite end, but this does not give much time for the heat to transfer to the coolant. Doubling the distance will double the potential heat transfer. Therefore an internal U in the block may help. A more complex design is a Z layout with three lengthways holes, but this is not recommended as it resists the flow too much and is only suitable for the GPU block.
The Z design illustrated will have problems venting any bubbles unless placed to allow any trapped bubbles to flow upwards. You may notice that in the Z block I have added two very small cross holes which will help expel air even when the unit is placed in any position.
The drawing shows a transparent unit for illustration only. Do not attempt to build a heat block from clear plastic nor glass, as the heat transfer and material properties are not suitable.

The best GPU cooler would ideally have lots of internal channels, as shown in the CPU block under test in the picture opposite.
Many internal holes present a large surface area between block and coolant, to give greater heat transfer for the design. This is only possible if you are good at drilling straight holes. If your holes wander while drilling, then use a new drill bit, or sharpen your drill ends more accurately. Always ensure that the total cross section of the cross-drillings is slightly larger than the bore of the main coolant flow, so that the device does not constrict coolant flow. More on drilling holes later.

You may happen to notice my butane powered 'Prescott CPU emulator' in the picture. After many minutes, only a three degree rise was observed and was considered more than adequate for this approximate 400 watt heat source, - despite using a small waterwall radiator without active cooling and the pump running at very low speed. Yes, this 'simple' drilled block of alloy works a lot nicer than many CPU and GPU headers available commercially.

The illustration shows a design allowing all three items - GPU and two memory blocks to be positioned for best flow when mounted vertically. This can be hard to make and fit, so only attempt the memory if the main block was really easy to make. The plumbing must be neat, yet not interfere with the AGP or PCIe socket. The PC motherboard and case is designed to take very long cards, so the pipes could exit at the rear of the card for low profile desktops, but this brings the pipes close to the front of the case. In practice, the pipes often exit from the top of the graphics card, so the plumbing remains short and neat.
The headers must not be obstructed by the various capacitors and other items on the graphics card. I occasionally reposition awkward capacitors to make life easier. Ideally, both pipes would enter from the same rearward or upper side, according to your machine, but this is not always easy. See later.

The layout is typical of most graphics cards, with the memory banks to the right and also above the GPU. In this example, the coolest coolant enters the GPU first, as this is the hottest item, then exits high, to ensure no bubbles occur in this critical area. The coolant then flows first through one memory bank then the other, exiting at the top, where any potential bubbles could be seen to exit. The first memory block will cause a bubble trap and so this has a small cross drilling to allow any air to vet from the inlet side to the exit, but the small hole is not big enough to allow significant amounts of coolant to bypass the block.
You will note that I have not thought this sketch through well enough, as if I was clever, I would have extended the upper edge of the lower memory lump, and not have to have soldered up a brass pipe with an angle bend or need to use a curved plastic pipe. See small black lines. Luckily, small alloy blocks are cheap if you know where to look, as they are often scrap items from an engineering firm. My latest design uses a single L block with multiple channels. Therefore always think things through beforehand, because pencil and paper is far mightier than the hacksaw and drill and far cheaper too.
The other design point is making all the inlet and exit pipes line up, with a little gap between them. This gap is to keep plumbing neat, but still allow a small amount of flexibility in the plastic piping between each component, so that each item will be able to lie perfectly flat over their respective chips when clamped or bonded into position. If very close, then make the connections a single brass pipe, with a loose fit, and then epoxy the tube in place, with the coolers positioned over the GPU and memory for perfect alignment while the epoxy sets. If you do not like the short stub pipes, then simply mount the pipes outwards, then use short U bends of plastic piping.

With my latest designs, I reposition capacitors then simply carve just one large block of alloy for the memory on each side, then decide the best drill holes for the position of the card. After lapping the bases, use 2 part epoxy 'metal in a tube' to connect the tubes between GPU and memory. While setting, I clamp the items in position to allow for the differences in height for perfect heat transfer.

Once the design is decided, the alloy GPU block is drilled. As drilling neatly aligned holes is a pain for beginners, then start by making centre punch marks, an old nail will do. Then drill smaller holes, as these can be drilled larger later, especially if they do not wander from the intended path. Also drill the larger inlet and exit holes using a small drill, as there is a booby trap of drilling through the larger holes first, will cause the cross drillings to go off line. Therefore drill the many small cross holes first, then the main inlet and exit drill holes, all using a small drill bit. Then drill these holes to the required, larger diameter, where the smaller holes will act as a guide.
If your cross drill holes wander and cross into each other, don't worry, it just makes for a slightly more interesting cross coolant flow. Carefully clean out all holes and blow and wash clean. Dry thoroughly by warming, then plug the cross holes with alloy slugs, and / or epoxy resin or two-part, instant metal in a tube adhesive. Then clean out the tubes again, using a drill down the inlet and exit holes to clean out any excessive adhesive. Finally insert the brass inlet and exit pipes, using a snug push fit and more adhesive or instant metal. Pressure test by blowing air into the item whist underwater, as bubbles show up any small holes.
Tip: Use a little washing up soap to help 'wet' the internal surfaces when cleaning through, to help the bubbles leave the block easier. If the internals have an oily surface, then the small bubbles may remain during use in the computer.

If the GPU block cannot allow the water pipes to enter from the side, then you can place them at an angle, but this will need epoxy resin or 'plastic metal in a tube' alloy plugs to fill the holes. Always make sure the brass connecting pipes have sufficient length into the GPU alloy block to support them securely. Alternatively make tightly bent brass pipes by heating, then filling them with solder, bending over a soft wooden former, the melting out the solder. If you are making a supremely neat system, then fit the CPU and GPU header inlet and exit pipes last of all, so that any mounting of bends can be refined.

Very carefully lap the mating faces of the block on a piece of glass, using some brass polish or other abrasive cleaner. This will give a perfectly flat and clean surface for the heat paste. The pipes can now be connected to the pump and checked for good flow through the blocks. A simple syphoning test using two pipes and a jug of water will do the job, as for primary testing mentioned earlier.
Connect up all the bits and measure into a container over a minute. If it is appreciably lower than the intended flow, then perhaps you have too much drag in the system and be constricted. If you have a 1 litre container and testing over the sink then you can fill the container to check against the time taken.

Mounting the header can be a problem.
If finding a suitable spring clip is difficult, then make your own. I deconstruct the cheap little spring loaded plastic DIY clamps for their springs, (usually four for a quid), then make alloy or steel arms to use these springs. The final items are low profile and the springs are available in many sizes. If wanting to experiment first, then simply use the clips as bought, but always make sure they clamp over the centre of the GPU and memory, and if this is over glass or plastic then do not use a strong spring.
Where spring clips such as Terry Clips; flat as used for draughtsman drawing boards, or curved for holding tools.
If other mechanical restraining devices are not easy to retain the cooling blocks, then they can be bonded in place with thermal epoxy resin.
As glue is a one-way process, then it is better to use thermal paste on each item, but employ a dab of epoxy on the inner corner of each chip, which will allow a reasonable chance for removal without damage. Do not use superglue, as this sets instantly. This collection of items will need careful positioning and need an individual weight over each to ensure they are perfectly aligned to the chips while the epoxy sets hard. The faster setting five minute epoxy is less strong than true epoxy, but is plenty strong enough for holding this in place with a dab in the corners, with the thermal paste in the centre of each chip. It will also allow easier removal at a later date when selling the card at a car boot sale with the old cooling fan carefully replaced.
An option which is believed to work, is to mix thermal epoxy with equal amounts of normal thermal paste, to give a less strong bonding process.

The GPU is usually capable of being clamped in place with mechanical restraints acting through the printed circuit board. If making a mechanical clamp device and not bonding in place, then always add a central dimple, and a corresponding centre punch in the clamp, so the cooler remains accurately in position.
Personally, I prefer to glue just onto the inner corners of the memory chips, as this allows for differing expansion of the components with minimal distortion then clamp while setting. As there are often two memory chips, simply gluing just the inner corners will usually do the trick, but GPU coolers are best clamped using through bolts and a spring loaded arm. Don't forget to lap the alloy bases first and a dab of thermal grease.

This kind of stuff is not expensive, apart from the copper sheets or alloy blocks. The rest is simple hobby stuff, with a touch of engineering and common sense. Total cost should not exceed a fiver.

The picture of the graphics card also shows the suitability for making the memory block as a large L shape of alloy for convenience, but only if all the memory chips are level with each other and you have a spring clip which will allows for different expansion rates.
As can be seen, the interconnecting pipes are short, so full length plastic pipes will be needed, and these are best retained by using steel or copper wire to make three turns then twist the ends for a secure seal. Do not attempt to reduce the gaps, as this is needed to ensure the blocks seat perfectly on their chips. A minimum of 5mm is usually needed, especially between GPU and memory blocks. If possible, simply reposition any obstructing capacitors and build a large single memory block. A large L block is possible if your drilling is accurate. If not, then drilling from both ends to meet in the middle is easier, plus blocking both ends. Never let the brass pipe inserts block off the coolant flow, but always make sure the ends are chamfered where needed.
Another aspect of this design is to decide the routes of the pipes to and from the graphics card.
The main point to note is to ALWAYS sit down and make a full size drawing of the graphics card, the position and height of the GPU, memory and any obstructions. Then work out where any plumbing can be positioned, in a manner which can actually be physically made, in a manner which will work efficiently, reliably and safely.

When your coolers are ready, then carefully lap the surfaces so they will be perfectly flat and thus transfer the maximum heat through the thermal paste. Lapping is done by gradually smoothing the mounting surface to a perfectly flat surface to mount onto the chip. There are lapping kits which cost money and consist of gradually finer sheets of abrasive paper. I simply make an initial flattening using fine wet and dry, while it is placed on a sheet of plate glass, which is perfectly flat, then I use a commonly available metal polish. It's important to keep the metal block level when lapping, otherwise it will become slightly domed, although this is not a problem as the centre of the dome will be perfectly positioned for the reasonable heat transfer, but it is better to have perfect heat transfer from across the whole chip. To maintain flatness, use plate glass and use a small figure of eight motion, using all the plate glass, with the pressure always acting in the centre of the block.

The alloy cooling block has a problem, as many people do not have access to such blocks of metal, nor are very good at neat drilling. It also needs a strong mechanical retention device to hold the alloy in position on the motherboard. Its main advantage is that it is easily removable so you can return to the original manufacturers heat sink.

Another alternative is to make a simple plate to mount on the GPU and memory, then build up walls and a lid.

An easy option is to make simple brass or copper plates to mount onto the memory chips, then solder a carefully crafted brass pipe to these, so the coolant draws away the heat.
A single, long, snaking pipe is ideal for the memory chips, flattened slightly where it passes over the memory pads, so a little more heat is transferred with plenty of solder for the heat path. These are much easier to make, but needs to be done carefully, with a neat, flat wooden jig to ensure the soldering process keeps all the plates perfectly level, followed with a little lapping for the heat sink paste.
To make a snaking brass pipe, fill the pipe with lead or solder. The brass pipe can be crimped at one end, then heated as the lead is poured into the pipe. Then the pipe can be carefully bent around a wood former, until it passes over all four memory chips. The pipe is then heated to remove the lead and is a 14th century trumpet making technique.
Then the memory heat sink pads are laid out on a nice, flat wooden block, the pipe laid over and heavily soldered.

You can go further.

Such cards may need over clocking above and beyond the 'call of duty' and a far cry' from the manufacturers standard specs and 'doom' may ensue.

Only those who want to push an old card will be open to a little further, er, development as mentioned next. It is also much easier and far cheaper to build and far more efficient if done well. But it needs total commitment on the part of the card.
If you are running your GPU close to burn out, then you may wish to 'cool direct', but only if NOT mounted in a mini tower fashion. The motherboard must be used upside down, BTX style. The following has NO room for any bubbles.
I place a piece of plasticiene over the centre of the processor and memory chips, such that a wall can be built direct on the chips. Then build them up with interconnecting tubes for direct water cooling, - WITHOUT an intermediate alloy or copper heat skink. This gives direct water-cooling.
You must ensure the water is permanently against the chips, otherwise they WILL burn out, especially the GPU, so clean the surface of the chips appropriately.

WARNING: Some silicone dies are set above the body of the chip, so if you can imagine it upside down in a mini tower case, then there is a very dangerous place around it for air to accumulate. If so, then leave well alone, or use a desktop case, or like me, simply turn your motherboard upside down, BTX style in a home made case.
WARNING: Some graphics chips have surface mount capacitors and on their upper surfaces, along with some laser cut connections. Therefore it is important to prevent these from water, so apply a little lacquer.
Place a block of plasticine onto the chips which can later be removed, then build up a wall using a non conductive paste such as hard setting resin or 'plastic metal in a tube'. At least 70 percent of the memory chip upper surface must be open to the water, but in most cases, the wall can be built up on the surrounding mounting area. A slight taper, plus grease or cling film helps remove it after the wall has set. Perhaps you may wish to make a neat little wall first, and then bond this in place.
If you want to get really sexy with this system, then look up the art of 'fluidics', which was important when I got a job designing some or other cooling stuff for nukler reactors.
I never touch any GPU silicon, but build the wall around the larger surrounding mounting plate, although I apply a smear of silver thermal grease to protect the silicon from long term corrosion and the coolant is always distilled water.

I prefer to slightly rough up the plastic surface of the memory to make a better adhesion of the plastic metal in a tube. I recommend that you study the memory mounting closely, as some are hidden surface mounted, some are still using legs. Either way, you must prevent any non insulating material does not intrude between the chip connections. If room is tight, use a small bead of silicone sealant around the lower edge first, to seal the electrical connections, then use plastic metal in a tube on the actual chip. This way, any conductive materials will not short out any memory legs or circuitry, should a leak occur and drain into the soldered memory chip connections. Some hair lacquer over nearby components may also help after a very neat and clean build.

Always decide first where the pipes are to go for the layout in your machine. I always cool the GPU first, then the memory in such a way as to ensure good flow to all. A small vent pipe is often required from the GPU to the outlet on the last memory chip in the coolant run, to help remove air bubbles. If you place the exit of the small vent pipe just inside the larger exit pipe, then you have active purging.
Cut and layout the large bore pipes to make the most of your card design. Some graphics cards have the GPU and memory at 45 degrees to enable a very clean coolant run in any position and eliminate bubbles very easily. ALWAYS make sure they there can be no air bubbles. - With alloy blocks, the chips will still transport the heat from the chip surface and you can get away with a few bubbles in the system. But in this design you do not have this advantage, so there must be coolant against the face of the chip at all times.
It is possible to lay your pipes in position first, possibly squashing a brass tube to keep it all neat, then build up around the tube. I seriously recommend you place the interconnecting tubes close to the surface of the chips, as they will usually be upside down in an ATX midi tower case, so any bubbles MUST be removed easily. Careful pipe work pays dividends. Include smaller venting pipes or channels where needed, as the card may later be used in a micro system, desktop, ATX or BTX or special.

Another main point to be considered is to ensure the pipes are able to take the physical handling force applied by the plastic tubing to the pump and radiator. Rough handling when fitting the interconnecting plastic pipes between pump and radiator can cause problems. This can impart a high force and cause the coolant channels to be cracked or pull away. Therefore always fit a mechanical restraint for the exit and inlet piping to prevent any force being applied to the channelling. Always try pulling on the pipes to check before inserting the card in position. Also check with a test run for leaks and safe coolant flow and ensure perfect bubble removal in the intended alignment.
When all the walls and tubes are built, you can then use more paste on the walls, then use cling film and a sheet of glass for an inspection covering. Then silicone sealant and preferably a mechanical retaining bracket.

Although this seems a permanent solution, it can be carefully removed if it does not work out too well. Carefully applying a sanding disc by hand, then rubbing some fine sand paper over the memory chips will allow the original heat sinks to be replaced. The GPU surrounds will also need some neatness, but the GPU silicon itself should never have been touched.
It is important that the positioning of the tubes is very easy to get almost perfect, so the plumbing can be built to have pipes positioned for both mini tower and desktop layouts.
WARNING: Remember that most GPU's in a miditower are upside down, so be wary so that any bubbles will be away from the GPU. If you over clock the GPU too far, then check for steam bubbles by which time the chips have probably died. But the chips should never be allowed to get beyond 60 degrees. If you push too far and there are no bubbles, then at least you will know it was not through lack of direct cooling.

It may seem a bit of a pain to regularly check the state of the cooling for air entrapment over the GPU. The simple answer is to temporarily stick an old web cam up close and add a light. If it does not focus too well, then use a watchmakers eyepiece and a splodge of blue tacky putty as used in offices.
More simply, adding an LED in the wall of the GPU and a small plastic mirror at 45 degrees will allow the ultimate in GPU 'modding', where pretty lights are for proper and sincere reasons for a 'bona fide' modded computer.
Inside the GPU hollow, I would include two white LED's connected to the 5 volt rail to allow direct visual checking, plus a couple of thermo sensors should things get hectic. Cheap LCD digital temperature sensors for general purposes use can be run from independent 1.5 volt systems for direct measurement. Buy a handful when they are cheap.

You may want to put some heat sink clips on the larger capacitors too. They are available from electrical suppliers or make your own larger finned items using scissors to make a fined alloy device using scissors and a cola can, held in place with O rings or a nylon tie wrap.

This is not real modding, as it does not include pretty lights or fans - and it is very naughty, because you may also invalidate the manufacturers warranty :)
Please do not follow the above few paragraphs, even if you have a spare graphics card that you wish to torture slowly and constantly as if in Guatanamo Gulag. You know it's not right.

Have you been reading carefully like good little boys and girls ? Let's find out:

I'm unemployed and Anglo-Saxon, (gizzajob). For these sins, I was unfortunately trained as a teacher of technology and design, (B.Ed) and happen to have a science degree, (B.Sc) and HNC in refrigeration, a registered engineer blah, blah etc, and been modding computers since BBC'B' days, but like so many today, no job in this once great country, but now a shit hole called Britain.
So let's see if you have sense of humour too !
As a final test piece, here is a truly scrumptious X800 pro in a micro case.
Please note that the graphics card has its cooler removed, but only to expose the central GPU and the four memory chips on each side for clarity. (4 memory chips on the reverse side too.) The GPU is believed to use all its memory pipelines to XT spec by joining the laser cut in the top right hand side of the GPU, and has a bios flash to XT. 'Atitool' and 'Powerstrip' on the HDD shows it may be in fear of being overclocked.

For five points, draw a possible route for the water-cooling through the graphics card. Assume the plumbing exits at the rear of the case.
For five points, consider where you would put the pump.
For ten points, choose the THREE best positions for the radiator and the THREE types of fans which could be used.
Being such a small case, decide if you would you need any other considerations.

Give yourself extra points if you do NOT use any expensive materials or processes.

You will also get points if you can over clock the machine to the fullest extent of its potential for under TEN quid. This must include a radiator and pump.

If you do really well, I'll promise not to recommend you for any daft GNVQ.

If you decide not to water-cool, - and that's valid too - then separate GPU and memory finned heat sinks could be used. The GPU would have its own fan, but if ducted well, then the memory fins on the GPU side can be cooled via the GPU fan, simply by adding cooling fins to the memory chips and cutting slots in the cooler to ensure they are in the draught. I would probably not risk shimming on this chip. A small fan such as an old 486 fan can be used for the memory chips on the other side, using some cardboard ducting from cool external air which can be powered via the motherboard for speed sensing. As the card is close to the side of the case, then it can be separated from the rest of the machine and vents sin the side case can create a full flow, cool air system all around the graphics card. I would make Jaguar E-type vents and a cardboard insulating wall.

Here is a close up of a hot nvidia card sans heat sinks, showing almost identical layout.

If water-cooling, the cooling could possibly be via alloy or brass blocks, preferably narrow to fit inside the limits. This would need smaller diameter coolant pipes and a higher flow rate. The smaller pipes would also allow a more compact pump and allow easier access to an external radiator.
If possible, I would look for a space to make a very small hole in the printed circuit board between each pairs of memory chips, so that a small wire can be used to clamp the coolers in place, as making suitable spring clips would be a real hassle. A very small hole with a fine piece of piano wire, nylon sleeves and an external spring from a car body panel or drum brake pad would suffice.
As the graphics card is vertical, then direct water cooling is possible and easier to prevent air bubbles.
There is no room for the pump and radiator in the case. To improve the pipework, I would have the inlet and exit coolant brass pipes neatly bent to exit through the rear mounting plate, which would prevent any damage and allow much easier fitting.

As there is no room inside the small case for a decent radiator and the CPU also water-cooled, then I would place a thin radiator externally across the side, as it would otherwise obscure the power supply exhaust of such a small case. To keep things as compact as possible, I would use a large, thin radiator with a very fine matrix. To make a neater arrangement, the upper and lower headers of the radiator would be long and made to blend into the shape of the case. This would require more cross pipes and an internal upper baffle so the water flows fairly evenly though all cross pipes. The cooling fans would be small and many, or a long, thin and rotary fan, positioned to the rear of the long, dual pass, multi-tube radiator with upper and lower headers. If this was difficult for some to build, then I would consider a large alloy, crinkle plate radiator, not dissimilar to some domestic heating radiators.
The various types of radiator could be home made - see later.

A set of chrome 'roobars around the case would keep things nice and tidy as would a polycarbonate screen to keep the airflow over the radiator fins, but would add 1.5 to 2 inches extra width to the outside of the case. This can be made from chrome tubing from an old towel rail, motorcycle handlebars or similar items. The curved sections would be cut to size and rebuilt using smaller internal sleeve tubes, soldered to keep the structure rigid, although a welded structure would be preferred. This could act as protection for an external home made radiator, and also a secondary radiator, reservoir and carry handle.

Radiator alternative 1. If not running a fully overclocked top processor, then the radiator could be mounted to the rear, but ducting to allow power supply exhaust would need it to extend 3 inches beyond the rear and could obscure the inlet and exit of sockets, so it would need to be hinged for socket access with flexible pipes.

Radiator alternative 2. This would be to mount a thin radiator on the roof, with axial fans ducting across the large radiator, exhausting to the front. It would also keep the obligatory 'cup of tea and perhaps a biscuit' warm for an extra mark.

Radiator alternative 3. If the outside dimensions of the case could not be compromised, then a radiator and large fan could be squeezed between the rear of the card and the face of the case. This would suck cool air inwards, through a large opening cut into the side of the case. This could draw air through the case, although may be at odds with the power supply fan flow. If the flow was compromising the rest of the machine, then a series of extra vent slots could be cut into the case itself, beside the graphics card, near to the rear side of the case, with ducting around and behind the card to keep the graphics area and radiator airflow separate from the rest of the machine. This would give the side of the case beside the graphics card the same slots as in a E-Type Jag bonnet (hood). A compact water pump or an external water pump may be needed as finding any extra room would be almost impossible.

As you will have discovered, a monster GPU in a micro case id not all doom.

There are many options and all will depend upon what the builder wants in their computer.
The small case would not allow a header tank, so it would be a sealed system. If using an external radiator, then the plumbing from the GPU would be direct through the rear panel, to an external pump to keep it running cool and allow direct adjustment. As there are many wires leading from the rear, then a small pump would fit in the unwanted space between the rear of the case and the wall.
Because of the small case size, the pump would probably be thermally controlled for speed, from a temperature sensor in the GPU header, and/or CPU header. The temperature sensor would be two speed, set to spin the motor at full speed when the temperature rose too high, but otherwise the pump would be in a 'high tick-over' mode. A speed sensitive circuit is possible, but would add extra complexity and less reliability to the system.

At present, I also embed a couple of thermistors into the moulding of the GPU headers to allow for future expansion and control, using PWM motor control, one of the many ideas I'm experimenting with at present.

As the X800 memory chips are small and directly cooled by the original heatsink, I would make up small, individual copper sheet and soldered water jackets with internal brass baffles or copper brake pipe snake coils. These would also have large, flat brass cooling fins, and the side of the case would be sucking in cool air over the graphics card. The main GPU cooler would be alloy with a small window in the side of the case to highlight any excessive modding.
I would water-cool the CPU, but would build a special water pump for reliability and low speed torque with low pressure commutator brushes for longevity.

Alternative 5. For sheer simplicity, you could simply put a huge draught through the whole machine, using seriously ducted internal aerodynamics and a pair of large fans. I would use home made, cross flow 'flower' style CPU and GPU heatsinks with 'percentage ducting'. It would not be too noisy if the internal airflow is not restricted. Only coarse speaker grille cloth or highly perforated metal mesh or preferably metal 'Venetian bling' vents would be needed at front and rear to reduce restriction and minimise noise.

Alternative 6. To get a decent heat differential across such a small internal radiator, I would use refrigeration. My present design of micro 'fridge pump would do, but is a little too noisy at present, but will fit inside a dummy CD drive or preferably mounted neatly and matching under the case. More to come, if I can get fifty quid to fund research.

As can be seen, there is more than one answer to every problem.
I'm sure you created these and a few of the other options besides, a couple of which are mentioned later. If you did not, then make a cup of tea, and perhaps a biscuit. Then sit down and use your brain in free flow mode. The brain does not need to be connected to a computer to work.

That should do for a while. If you need more ideas, then I've included below, some more that you've probably read before from this website.

A high specification machine, with CPU header and a waterwall radiator (see below) and a decent graphics cooler can be a work of art. Even more importantly, the cost of the bits and pieces need not cost more than a tenner.

The bottom line, of course, is that when it comes to simplicity, good old 'air cooling' has certain advantages in the simplicity aspects of design. The art of 'mega-aircooling systems' with a few clever tricks is also possible especially for overclockers, but is still under development using airflow testing in micro AXT desktop cases. (See my monograph on aerodynamics and wind tunnel design and building.)

I am toying with surface evaporation cooling to get the temperature down a little below room temperature. This is done by creating a film of water over air cooled fins. But this needs a small watertank and metered gravity feed, but presently makes a damp mess around the CPU as the total-loss coolant wicking is not quite perfect. But if the CPU fins are shaped appropriately, then it can work. The main problem will be in fin design and a wetting solution to allow the coolant to flow over the fins and evaporate easily. If it dries out, then these fins must still cool the processor, so I cannot use cloth or plastics, but a special form of metal mesh which can transfer heat when both wet and when dry. At least a pint should be needed as the reservoir, and so only suitable for midi tower cases. This reservoir would be insulated and allow adding ice cubes, plus a low level warning. This simple design could be easier to build and fit than water-cooling and should get even lower running temperatures than water cooling, due to the surface evaporation effect and the chance to chill the water before reaching the fins. But perhaps some ideas are best left alone. Email me if you are interested in more of this particular line of thought.

If water cooling is not good enough, then it's time to make your own freezer unit for the CPU and GPU. But that's another story, again not so difficult as you may think. It can also be very cheap and you are probably not surprised to learn that there are many ways to do it. More later.

Well, that's about it for today,
I know there are a few things I've left out, so may add them later.
Any decent computer modding website is welcome to make links to this page if they wish - just ask first.

Below is my earlier guide to water-cooling, written before you could get the various bits and pieces at their present low prices.
This second part gets into making your own stuff, and is mainly for those who like to get their hands dirty in order to make the ultimate in computer systems. - Not ultimate as in expensive, after market junk, but in making really decent systems capable of real improvements in cooling and in style.
If you failed woodwork, or never completed a model aircraft kit, then leave now.

My website has monographs on building your own computer and interfacing computers to make your own stuff such as full size wind tunnels at home. Plus lots of other interesting stuff too, such as fixing a tap ! For those who are not too good at hand skills, I build a few, affordable and fully tested, made to measure computers from 600 pounds with 939 CPU's dependant upon the spec you want.
From decent to decadent, to ultimate, Just ask. All fully tested, optimised and gamed hard before delivery.

Water cooling.: Expensive - right? Well, no actually.

Finding the ball park: Some basic arithmetic.

Water has a thermal capacity of 4200 joules per kg per degree C.

That is to say, to raise the temp of 1 kg of water by one degree, you must pump in 4200 Joules of energy.

1 Joule per second is a Watt.
A typical CPU pumps out between 40 and 90 Watts. I'll assume 70 Watts.
70 Watts in one minute (70 joules x 60 seconds) = 4200 Joules of energy.

1 litre of water weights 1 kg.

Therefore, to raise the temp of 1 litre of water by 1 degree, simply apply a 70 watt CPU for one minute.

My old, discarded car wind screen washer pump, pumps out more than 1 litre per minute.
This 1 litre of water is 1 kg water per minute.

Therefore in one minute, using 1 kilogram of water and raising it by just ONE degree, it can absorb 4200 watts.

Check:
Specific heat capacity of water = 4200 Joules per kg per degree C.
1 kg (litre) of water raised by 1 degree absorbs 4200 joules. One Joule per second is a Watt.
70 watts for 60 seconds = 70 x 60 = 4200 joules, the same as needed to heat a litre of water by one degree.

(An aside for those who wasted their potential in their maths and physics lessons.
If you placed a 1 litre container of water on a CPU and it is placed in a room at 30 degrees, and the maximum temp permitted was 90 degrees to prevent the CPU from cooking, then it would take 60 minutes to reach 90 degrees.
Overclockers may see this as a machine capable of an hour's use before needing to use a radiator. I see it as having to wait a whole hour for a mug of tepid tea. Oh, the vagaries of lateral thinking.)

(For thermodynamicists wanting to squeeze the last half a degree out of a high pressure system; P1xV1/T1= P2xV2/T2. If V1=V2 for maximum cooling effect on the CPU, place the pump between the return leg from the CPU header to the radiator, then insulate the pipe from radiator to CPU header to keep it cool from internal heat of the computer case. P Pressure. V volume. T temperature.
This theoretically would slightly increase the pressure P2 in the coolant as it passes through the radiator, increasing the heat differential, with a lower pressure P1 after the radiator, slightly cooling the coolant as it is pumped direct to the CPU. But in practice, the differences are almost impossible to measure and probably less than one tenth of a degree.)

A recent computer magazine bestowed praise on a commercially available pump - MCP350 - which pumps 90 gallons per hour and was recommended for water-cooling a computer !

Let's look at these figures a little closer.
Assume 4 litres per gallon. (3.7l=1 US which is also 4.5l =1 UK gallons.) 90 gallons per hour = 4 x 60 = 360 litres per hour. This is 6 litres per minute.
This is about right as it is about six times more then will ever be needed and probably about twenty times the output for a decent radiator running a cooling system with a ten degree heat difference between CPU and radiator.
The magazine also mentioned the (MPC650) which can transport 300 gallons per hour which is simply going stupid.

Back to the real world.
From the numbers, you can see where this is going - and it's looking very cost effective.

If it is possible to use an old car screen pump which can deliver a litre of water per minute, then why in hell do I need a special pump which delivers massively more litres per hour. If the water-cooling experts have got this wrong, what else have they got wrong and why in the name of mad religions should I pay good money for a 'professional' computer water cooling system?

In modern Britain, the term 'expert' is now often used as a derogatory term. - GM crops, dodgy police forensics, cloning of human embryos and other obscenities done in the name of 'science', but actually done for greed, profit or power.
Always keep your eyes open. Don't get suckered even at the lightweight end of crap British science.

Let's look at the pros and cons of water-cooling.

The computer is a professional piece of kit and costs money.
You are not going to be water-cooling an old hack, or even a half decent machine, at least not yet, until you have done your development and testing. Even I use fairly new intel lashups given away because they do not work, (or did not until I fixed them). One test rig is made from motherboard and memory and graphics parts thrown away from my local PC Craphouse mega store and yet I've got it to work.
So unless you deliberately seek out disposable test rigs, you are playing with the life expectancy of a rather expensive piece of silicon.

Cost, what cost ?

Most local car parts shop offers three generic choices of screen pump for under seven quid. The differences were in mounting and general shape and the outlet and inlet pipes. I choose the simplest one. Although it was not very quiet and made of plastic, it did the job. The screen pump had small inlet and exit pipes for 6mm bore pipes gave a flow rate of just over 2 litres per minute at its standard 12 volts, but at 5 volts, it managed to pump one litre per minute. In both cases it was rather noisy. Unfortunately this cheap plastic bodied pump could not be dissembled without permanent damage, so if it was to be used, it would have to be sound proofed by encasing in a sound absorbent material.
If such a pump is expected to have a ten year life span on a car and used intermittently, then perhaps it is suitable for just one year of 4 hours a day, every day in a home gaming computer. I would not trust such a cheap pump too far, as it is built down to a price. The garden cheap pump begins to look more promising, unless you are happy to buy a new pump each year for four quid and dissemble the old one to see how long it could last in your rig. By running my pumps at half voltage, I am sure this would quadruple their lives, but this is an ongoing project and is not yet proven.

For better integration of a screen washer pump and for longevity with silence, I prefer using a video recorder motor which, although not as powerful, is at least designed for long term use and particularity quiet. This is the tape transport motor which is designed for light, constant use for hours and is often just a simple CD permanent magnet motor using a separate feedback system to maintain tape speeds. It can run for days without hassle and ideal for variable speeds. There are also chokes and suppressers in the video motor to assist an easier life within electronic systems. One of my video motors even has ball races.
The screen washer pump motor on the other hand is simple and reliable, but not high quality and designed for short bursts at max speed. If just wanting the pump itself, then this is probably a good starting point for a cheap second hand pump body component for modification and testing, even if later, you don't keep the original motor and use a video motor.

Let's look at just what a pump has to do.
It merely has to transport the water around the system. The computer is a small system, with minimal restrictions and a low pressure regime. There are no isolating valves, restrictors or other such malarkey, and it is not run under pressure, so this is very simple. The only consideration is if using a system where the water has to be pumped up to a 'head' such as in a garden fountain. - More on this later. In most computers, the pump will have a very easy life.
Most commercial computer water cooling systems use garden style pumps. There are two types of garden pump, one for a high volume, low pressure such as a waterfall pump, and the low flow, high pressure type as used for fountains. The waterfall design is usually larger and more expensive. Most catalogue shops can supply the cheaper fountain design. It need not create a fountain inside the case, just the basic job of a gentle flow, so it is not going to be running very fast.
The average after market computer coolant pump is from a garden water feature, often for squirting water in a small fountain style, not dissimilar to a car screen washer pump. The flow is low but the pressure is reasonably high. As a garden device it's designed for constant use, so is low rated. The car screen washer is used very intermittently, so is more highly rated and closer to its limits, as it's not used too much during its life.

In reality, the average screen pump motor is not designed specifically for the screen washer pump and when you open it up, and inspect the internals, it is merely a generic motor design used in many thousands of toys and minor electrical components. Therefore it is designed for general use and reasonable longevity. But it is not designed for quality, just a working hack of a motor. So if you don't push it hard, it could even last for ever. It would be interesting to compare these motors with those used in commercial water cooling systems. - Probably the same items.
Both are usually small and the pumps are nearly always centrifugal vane type. This makes the pump simple and reliable and least effected by debris. If wanting reliability then simply buy a cheap one and run it for a month, then check it still runs smoothly. It wanting total reliability, buy two, run one constantly to find out its failure hours. Or simply make and use two pumps in the coolant system. Reliability is important.

The coolant flow rate is always a constant interest and in my opinion, miles from reality for most commercial systems. As mentioned above, the coolant must absorb heat from the CPU. Therefore the greatest difference between the cool coolant, and the hotter CPU will ensure a greater heat flow into the coolant. In simple terms, the cooler the coolant, the cooler the CPU. But it is the way the coolant releases its heat and cools down through the radiator, not the flow that is most important. If it can pump a litre or so per minute, then a fancy pump does NOT make the system run cooler.
But a system does not actually work as simply as that: The heat is supplied by the CPU and if the coolant is pumped around fast, then the CPU will cool down, but the radiator will still have to dissipate the same amount of heat. Assuming the flow rate is high, then the heat from the CPU will reach the radiator very quickly and cool down. But whatever happens, eventually the system will stabilise to a working temperature, dependant upon the room temperature and the amount of heat the radiator can pass into the cooler air.

In reality therefore, because a specific radiator design can only dissipate a certain amount of heat, most systems settle down to a working temperature range, where the flow rate is not terribly important, as long as it can transport the amount of heat required. The speed of flow away from the CPU to radiator is not too important, as it is the coolant temperature from the radiator entering the CPU header which keeps the CPU cool. The flow rate need only be large enough to pass the heat from the CPU to the radiator to remove the heat. If the flow rate is high, or low, the system will still stabilise to the same overall level, but the only differences will be a slightly longer time for the hot coolant to reach the radiator. Only the speed of any external cooling fan will improve the system down a little better, and then only to a certain limit, dependant upon room temperature.

If the coolant flow is very slow, the same amount of heat would be transferred, but the radiator would merely dissipate the heat with a slower flow rate, although the heat would still be transported, the system temperature would rise slightly relative to the coolant flow, until it reaches a flow rate which surpasses the ability of the system to remove any more heat. In other words, there is a flow rate above which very little improvement is achieved.
In this respect, with the slower coolant flow, the flow rate would reach an optimum flow according to the overall system, but there would be a higher temperature differential between radiator and CPU. Water has a very large heat capacity and thus it will change minimally in a stable system relative to overall temperatures between CPU and radiator. Therefore coolant flow need only be enough to pass the required heat from CPU to radiator.

The best method is to allow the system to stabilise at a high pump speed, then slow down the pump until the stabilised CPU temperature begins to rise. Then raise the motor speed slightly to be on the safe side. This must be done over many minutes as water-cooling has a massive heat reservoir and therefore the temperature changes will be very slow. This slow temp change also happens to give the computer a working safety margin.

A 70 watt CPU with just 2 degrees difference between radiator and CPU, needs less than a litre a minute. This means the pump can get away with very low flow rates and so a couple of degrees difference across the radiator is almost negligible. Therefore it can be assumed that the radiator will need more than a couple of degrees above ambient room temperature to dissipate its heat. In reality, five to ten degrees difference is going to work in the real world, and this means that the simplest car screen washer pump need only work at quarter its normal flow rate. As flow efficiency relative to voltage applied is not linear, then the pump working at half voltage should be more than enough for most CPU's. This of course, flies in the face of commercial systems, but works well enough on my systems. I will never be buying any fancy pumps, but prefer to invest in really good radiators.

A case where low power pumping is not suitable, is where there is a large head of coolant, such as in a waterfall radiator, where the water has to be pumped above the overall head of the system. Therefore it must be checked that the power of the pump is capable of sustaining this difference in head.
This head is unimportant tot he pump in a sealed system with no air bubbles, the coolant flows much easier, as the descending coolant also draws the higher coolant along, so the overall effect is negligible, not dissimilar to that used when siphoning petrol using a plastic pipe. In effect, the pump is simply working in a large pool (if somewhat convoluted pool and looking like pipes) where there is no fountain needing any pressure.

Let's have a closer look at the basic car screen pump.

The final improvement for reliability is simple; run the motor at less than full speed.

If your tests prove the pump can deliver a litre of water per minute, then this is more than enough flow as the above calculations do not want the water running a single degree above the CPU temperature, as the radiator simply cannot cool to this level of heat difference. Therefore a slower coolant flow will allow a warm running system, and a motor running at half speed is probably good enough. But always remember that final tests must allow the final motor speed to be adjusted for a reasonable CPU running temperature, in conjunction with the radiator fan speed.

Therefore the motor will probably be run at lower speeds to increase reliability and reduce noise. It is possible to run a 12 volt motor using the 5 volt rail from the PSU, but this is not going to give much control or adjustment. It can also upset the 5volt processors and memory feed lines, with a horribly spiky component to cause untold problems.

Motor control is better done using a reliable and robust component and the resistor is ideal.
Unfortunately, you do not know the final speeds, so a means of adjusting the motor speed is needed. Using a potentiometer is not ideal, as they tend to burn out under the large current flow. Standard potentiometers are rated below 1/2 watt, often far less. Ceramic types can be used up to 2 watts and is the type I use for small power designs. It is better to use a power transistor as mentioned below.
To check the values of a static resistor to reduce power, set a multimeter across the motor. My chunky car motors have 70 to 150 ohm, but for some reason my video motors have only 4 to 20 ohms resistance. As a basic guide, running it at half the current, I would use a 20 ohm variable resistor for full power to half power. But the heat dissipated by the resistor must be safe. Therefore the maximum power dissipated by the motor would be V x A = Watts. A= V / R, therefore 12 / 50 = 1/4 watt. To be safe, I would simply use a 1 watt rated 50 ohm linear variable resistor. This would allow me to adjust the motor speed by restricting the voltage available.
For a rough check of any motor, use a variable voltage supply capable of offering enough current in amps. Then increase the voltage until it seems as if it is screaming too fast, then reduce the voltage until it runs free without undue stress, then the voltage is about right. Most motors are in the 3 to 18 volts range, but if you are using a video recorder, then measure the motor voltages with the various motors running if possible.
With the resistor at zero resistance, the motor would get full power. With the resistor matched to the same values as the motor while running, both would share half the voltage, and probably run below half speed.

A more reliable method is to use a power transistor such as the simple to use, 49 pence TIP120 and a simple 99 pence 10k or 100k ohm resistor. ( Oops - spent some money ! )
The TIP120 is particularly recommended if using a commercial pump as they will burn out ordinary simple potentiometers, whereas the TIP120 is rated to 60 watts, if using a heatsink, but for most cases, a heatsink is not needed.
As this is a budget development, the screen washer pump has been brought up to a reasonable standard for indefinite running. The picture shows the transistor soldered direct to the back of a potentiometer simply for compactness and reliability. Take careful note of the back and front of the transistor for the correct base, emitter and collector connections.

Although the standard pump motor is more than adequate and should run happily for days on reduced voltage, it is noisy and needs sound insulation such as mounting in foam.

Rather than run a cheap animal of a standard motor, I prefer a more subtle design. The standard, very basic screen motor has no suppression and no balance, nor runs quiet, nor designed for constant use. Although as a generic motor, it is probably used in many other cheap uses and so would probably be more than adequate. Nevertheless, the world is awash with excellent scrapped components, and a good builder should always keep the eyes and ears open. So I use an old video motor as shown here. It is extremely quiet, smooth and designed for long term running. It only draws 160 milliamps at anything from 3 to 12 volts, while pumping water with minimal head. The shaft also happens to be the same diameter as the washer motor shaft, so the pump seal is perfect and by simply grinding a small flat on the end of the shaft and fits perfectly. I have also added an indicator disk to the other end of the shaft for additional visual checks. I collect these motors for free from old discarded videos for truly cost effective (free) computing mods.
If you are a scrap engineer, or as the Americans so nicely put it, a 'dumpster engineer', then you will notice that many small motors use the same components. The massive range of small generic types of motors all use the same diameter shafts. This makes it very easy for the manufacturers of small electrical items to use a wide selection of components, including the readers of this monograph.

You will have probably been given a scrapped printer and found a couple of interesting motors therein. Keep the stepper motor for CNC work and check out the DC motors for water pump use.

Under tests with a standard car screen washer pump and video motor, it delivers more than one litre per minute with a 12 inch head of water. At 9 volts it delivers just one litre per minute and at 7.5 volts begins to struggle.
But at 5 volts, the final design works quite happily because the systems I design have the pump working in a neutral head system. That is to say, with the inlet and exit being effectively at the same 'depth' in the system. So the pump runs happily at 5 volts while delivering plenty of coolant flow.
You can see that the end cap of this particular pump is affixed by screws. If buying a screen pump, then this form allows the designer three positions of pump pipes for a very compact system with very neat plumbing. It is also rather quiet.

This has cost nothing other than stripping an old video recorder, a light grinding on the shaft, deconstructing an old screen washer motor and applying some plastic metal in a tube to hold the bodies together.
The final design would be a little larger than the standard pump motor, but would have an extra bronze bush on the pump end of the design to reduce leakage into the motor body and have a very smooth, long use motor. The only other modification is to smear some silicone grease around the rubber O ring shaft seal in the pump body.
If the pump body inlet pipe is large bore, a piece of motorcycle rubber fuel pipe is used to make the coolant lines up to the bore used. I use this pump in both my small and large bore systems.

All I need do is to use some silicone sealant or two part epoxy adhesive to secure the pump body to the motor body and would still allow easy removal of all components for inspection and maintenance. To aid efficiency, I run the motor while the adhesive is setting, to allow the motor and pump to align harmoniously.
If the mounting is to be a tad strained, perhaps due to atrocious plumbing, I occasionally mount my motors in elastic mountings so they float in the case, with no strain from the pipes and introduce no vibrations into the computer case. Strong knicker elastic rules.

If mounting the pump in the computer case is difficult, simply make a box and use foam or a bath sponge to pack the motor. This offers the motor, pump and plumbing a flexible mounting. Always allow any coolant to leak out easily and stain the area underneath for a warning sign. A piece of paper or matt white under the motor mount is ideal, especially of the coolant is dyed slightly with some ink, perhaps from your inkjet refill or a proper pen.

Be wary of using old pumps, as if like mine, you have a worn shaft seal, then the pump could introduce air into the system.
If the seal is worn, then run the pump under water, using an extension shaft. As can be seen, adding a simple extension shaft using a piece of piano wire with a rubber connector allows the pump body to be submerged in a small, coolant filled container, preferably with bath sponge to hold it, but allow it to align and reduce vibration.
For me, a worn shaft seal is NOT a problem, but an opportunity. The small amount of air introduced will help indicate the coolant flow, but can cause a build up of air in the pump unit if not suitably designed with a vent at the top of the system and where bubbles may otherwise accumulate.
Always position the outlet pipe of the pump such that any air will bubble up to the exit pipe and be purged from the pump upon starting. I always ensue my whole system is not prone to any air build-up, as mentioned elsewhere.
If a new pump, you may not notice such problems until too late, so I always prefer to use knackerd components when testing new ideas, so the long term problems are part of the test schedule from the outset. Only then should you build a final version with new components (or new shaft seals.)

Fully check the pump, by running at all speeds, then check the flow and the height (head) of deliver is capable of reaching the high parts of the proposed coolant system. Check for leaks after three hours by marking the coolant level from the outset. Run for six hours pumping the water on full power. Then run from static on reduced power, to ensure the reduced pumping does not cause flow failure.
Warning: If it cannot handle six hours without any problems whatsoever, then modify or do not use the design.

During a long term test, you may wish to consider it a good time to heat the system to simulate your worst nightmare processor. I use a blow torch.

The test can be set up to check the heat flow using a calibration method. The picture shows a test session using my butane 'evil Prescott emulator' heat source, (a butane flame of about 400 watts) my video pump and the bottom of a waterwall before assembling into one of my series 3 custom cases. I'm testing heat input, coolant transfer rates, motor voltage and current, the running temperature of the water wall under room conditions and more than normal heat flow. This tests the whole system, pump flow with cool pump or warm pump and any problems with air entrapment in the CPU header and such like, and a close study of the overall coolant flow. I allow it to settle down and assess the needs of the pump.
In this example, the pump is running happily at 5 volts, draws 160 milliamps, NO cooling fans, almost silent and the radiator is merely tepid after fifteen minutes and never got warmer.

It is worth while leaving the system running all day or overnight, but only if you use a fuse just slightly above the amperage rating of the motor. As I use a small adjustable power supply, I've given it air cooling holes for extended running, as they otherwise tend to get overly hot and burn out transformer windings after a few years.
If you do not want a system connected to the mains and unattended overnight, then simply use an old car battery, a fuse to run the system overnight and place the water system in a plastic bowl.
Only use a flame to check the heat transfer rates over a set period of about half an hour, as any longer than this should not be necessary to allow the system to settle down to a working temperature for checking the heat transfer effectiveness. Never leave a naked flame unattended. If you want to apply a 70 watt heat source, then consider an electric soldering iron clamped to the CPU header and surrounded in glass fibre insulation to keep the heat in the CPU header area.

It is worthwhile on expensive overclocked machines to roughly calibrate the heat flow in the system. Therefore the primary heat source needs to be measured. I assume not everyone is rich enough to have a hot old CPU lying around to play with. To check the heat input, use a similar block of alloy, measure its temperature, then heat it for one minute and measure the heat difference. Using the specific heat and time, the heat absorbed can be measured and used for calibration of the heat source.
The typical butane blow torch can allow a variable heat source, but even the low settings are more than enough. An alternative is to use a 500 watt electric hot air paint stripper on low settings. These will not perfectly simulate your worst processor, but will certainly allow the system to be pushed to its limits.

While merrily testing on the bench, (kitchen sink) I also look for potential air leaks, noting where the bubbles are so they are eliminated before I fit it all into the computer. On test, the positions can be adjusted for the best and most reliable system. I also assess various pump positions for quiet running and self purging of any bubbles in the system.

When seriously testing in the case, then simply fit a small USB web cam and lamp inside the case, looking at the flow in the CPU or GPU.
With a three quid second hand screen pump, a scrap car heater matrix and a home made CPU cooler, then you will probably have spent no more than ten quid for the whole water cooling system and have a system three times as efficient than many commercial designs, and do so with minimal effort.

When I scrapped a car, I got discount if I removed the petrol and oil. I also remove the heater matrix and screen pump too! If anyone is scrapping a car, try to get the internal heater matrix, the screen washer pumps and plastic piping for the screen washers. Don't forget the small relays in the fuse box which can also be used for other projects.

Don't stop there, just because you have a good working system for pennies.
An advantage of building your own, is that it can be custom made to fit your case. I build my own computer cases, mostly transparent panels with wood frames. I recommend you have a try too, as they are very cheap to make.

If making a stylised case with clear sides, then not only the wiring, but also the plumbing must be impeccably neat.

I like to fit my pump on the base at the rear or front, dependant upon radiator positioning, so it can be easily checked and so that any chance of leakage will not reach the electronics.
The piping up to the CPU is such that I prefer to have two, neat, parallel pipes, the cool in from below and the hot exiting from above. As the motherboard is on one side of the case, I prefer the water cooling to be on the other side, and the radiator either at the front or rear. My waterwalls are on the side of the cases, usually employing ninety percent of the side area and with upper and lower internal venting for passive heat flow.

Using simple little pumps, I found that little coolant flow is adequate. My Intel test rig just refuses to get the system anything more than tepid, and then only after a long while. I really have a hard time noting any heat increase in the passive waterwall. I could run four of these processors on my basic water wall and still not get past warm. If I used a car radiator matrix and a fan, then it would be running very close to room temperature.

A pump need not be an active member of the system.
The pump need not be a passive member, but part way. In my nooklier design days, the systems were designed to allow coolant pumps to fail and still allow the coolant to thermo syphon. We were using liquid sodium if I remember correctly. Similar materials are used in true heat pipes. A computer coolant system, if using a thermo syphon system as mentioned elsewhere can still include an in-line pump.
For my fastest semi passive, ultra quiet cooling systems, a simple screen washer pump can still be included in parallel to the thermo syphon design, but to be used only when needed. The simplest designs have the pump beside the main flow channels, but with a side tap-off point to the pump and the pump outlet leading into the flow of the coolant such that is draws the coolant along using a slight venturi nozzle design. The overall flow would be minimally obstructed, but the pump could be used if the temperature becomes too high. This gives the best of both worlds: Silent systems, but with a powered backup. In emergency, even a radiator fan could also be engaged, but has never been needed to date.

Efficiency is not perfect.
The CPU header will not transfer the heat perfectly. There will always be a thermal incline between the surface of the silicone die and the water. Therefore the CPU interface should be thermally conductive, such as copper, aluminium or silver. Nevertheless, the CPU will still be close to the temperature of the water. But the system will need to settle down to a stabilised thermal incline, then hopefully the die will not get much chance to warm up beyond that of the water.

(DO NOT follow my example by building a direct water cooling on the CPU , using metal in a tube and brass pipes, so the silicone die is in direct contact with the water apart from a thin layer of lacquer to protect the silicon, capacitors and the 'overclocking tracks'. It also eliminates any need for cooling clamps and makes a very compact system. It may work well enough for me, but I only do this on older CPU's and then only for fun. I also increase the flow rate for the physically smaller intel CPU's. If making a very basic casing then use a piece of ice to create the cavity as you mould on the plastic metal and the brass pipes. Then very gently clean out the pipes and check for ideal coolant flow over the silicon. For most people it is far safer to build an alloy or copper CPU header which instantly becomes a heat sink in its own right and allows a few minutes use before coolant flow is needed to prevent CPU damage. )

The silicone die is small. On some CPU's, there may be a metal cover, but my favourite Semprons and Athlons offer the real thing - pure silicon - Barton style. The area is small, minuscule, and yet to get 70 watts from this means only one thing, a large heat path from die to water. The obvious is not unlike the 'flower' air cooler, a radiating pattern of vanes drawing the heat out from the die into the passing water. In reality, just passing the water over a nice block of copper or alloy or silver will suffice, as long as the water is kept relatively cool.
To maximise the heat transfer, the difference in temperature should be such that the water is as cool as possible, but this is limited in a stabilised system and so it is better to live in the real world, rather then chase the last few degrees. Ideally the CPU header will be a solid copper block about the size of the whole CPU and mount, to give a larger static heat sink, internally ribbed or channelled to maximise its surface area to the water, then covered in a water jacket which ensures the water flow has no dead areas.

I prefer to make the CPU cooler large enough to make sure of the four rubber aligning pads on the CPU, so the header sits nice and square on the die.
The latest processors use a plastic mounting, so I use the springiness of piano wire to make a mounting frame to restrain the CPU header in position. Preferably have simple locating arms to position it correctly within the plastic mounting frame. Making a retaining frame is usually simple, but never allow any strain on the pipes to distort the header from moving on the CPU. Even a few wood or plastic or rigid foam spacing blocks will suffice.
The latest CPU cooler mountings are not so easy as the older types. Therefore you will need to make up your own clamping systems. Always design the retaining clips to apply the pressure directly over the centre of the CPU die. You may wish to consider using piano wire diagonally through the four retaining lug holes. Then apply a notched wedge system to take advantage of the spring in the piano wire. Just make sure you apply enough force over the centre of the die to retain the heat sink in place. If moving your computer to and from LAN parties or whatever, then add some packing to keep it correctly aligned over the die. Do not forget to linish the mounting surface and add the heat transfer paste.
Never damage the motherboard mounting frame, as you may find that water-cooling is not always as wonderful as you may hope, especially if not overclocking.

Just passing a litre of water though a small tube in a header near the die is not good enough. Most of the water will not get directly near the main heat path in a basic coolant box. It is far better to ensure every part of the water gets a look at the hottest part of the CPU heat flow. Transferring the heat into the water depends upon the surface area of contact between the hottest spot and the water. This must not be a dead spot, otherwise it will develop a poor thermal incline. Normally, heat dissipates fast through water, especially if turbulent. There will be no steam bubbles, as your CPU will be dead by the time steam appears. To reduce problems, the hottest part of the die area should be dynamically purged with the coolest water, preferably over a finned or ribbed surface to offer the maximum area to transfer heat into the water. In reality, lots of small holes are drilled across the hot area, so the surface are available to the coolant is larger than a single drill hole and allows a small degree of turbulence to displace bubbles and prevent any dead spots. The heat will pass into the coolant, it just should be given a half-decent chance to absorb what is available before passing through.

Heat flows from a warmer to a cooler component. This, the 2nd law of thermodynamics commonly called entropy is what will cause the universe to fade into an even heat death. Every atom will eventually become moderately warm, with no difference in heat, thus no chance to generate energy between bodies of different energy levels, thus nothing will happen. The universe will get completely lazy and die.

For a few billion years yet, there will be a temperature difference between your CPU and the air in the room.
Water cannot be reduced below the ambient room temperature across the radiator fins. In reality the water will be a few degrees above ambient, if all is well.
The water temperature will not get down to the ambient temperature in the room. It is the difference in heat between the radiator inlet and exit which will decide the actual temperature of the water reaching the CPU header.
Overclockers do not want room temperatures, but want it cooler. This ain't going to happen without a phase change refrigeration unit or a Peltier heat pump or plumbing to outside the house if you live in a cold country and your computer is near an outside wall and you don't mind a couple of small holes. If below freezing, then always use antifreeze. Do not put your radiator in the refrigerator, as it is only designed to take away heat, then keep it cool with minimal effort.

The efficiency of the radiator and the ambient room temperature will govern the CPU running temperature. Calculating the heat flow in a radiator is far more problematic. How much radiator area, the heat difference between air and water, the airflow, and efficiency of the finning. Painting it black is not always such a good idea. Temperature differences, air density and humidity, fin area, surface texture, dust, - the variables are immense.

Assuming your room is at a warm 32 degrees, then you will have to work with a CPU running above this temperature. If you have a cold room, then the whole system will run cooler. If in a centrally heated room with double glazing, then tough luck. If lucky, your CPU may run at 36, to 38 degrees, but 42 or more is probably common. Don't knock it - this can hide very good heat transfer, even if the CPU is overclocked and running well above the limits of most air cooled systems, yet it can still remain at this sensible temperature, thanks to a good radiator. It is not near freezing, but who really cares when the system is most definitely keeping a seriously over clocked CPU on the right side of being too hot.

Calculating the heat transfer of a radiator is a nightmare, as the variables are hideous. For a real world, non scientific, radiator calculation, I'll use the car analogy. This is because it gives real standard, especially if using a car heater matrix for your cooling system.
With the temp gauge on normal, the car engine is running and using the internal heater and fan, then the car warms up reasonably fast. The car fan pumps far more heat than that in a computer. The car coolant is also around 80 to 90 degrees. A computer could not warm the car as fast as this. On a good day the car heater matrix is pumping out vastly more heat than a CPU could ever manage, probably about a 1 kW one bar electric heater, or about ten to twenty times the heat a 70 watt heater pumps out. Even with the greater heat difference of a car using boiling water and a bigger fan air flow, this is still a massive amount of heat dissipation in the car. If the computer radiator runs much cooler and in a warm room with a comparatively pitiful fan, then let's say the heat transfer is a tenth. This is still more radiator heat transfer ability than needed for a computer. If the car heater matrix can handle the 1 degree heat difference in the computer, rather than a 30 degree heat difference in a car, with a tenth of the air flow, this still makes the car matrix about five times more effective than needed, but probably just about right for a good safety margin. For a computer, a car heater matrix can transfer a good deal of heat.
Therefore there will be no problems with trimming such a car heater matrix to fit into a computer case, and the price is right too !

If the car radiator heater matrix is too large, then simply cut the radiator down. If it is alloy, then remove any header, and cut back the fins around the pipes to get the size you need. If a multi pass matrix, then this can be trimmed down to narrower or shorter as needed. When about right, the pipes can be connected using plastic piping and wire wrapping for security and the inlet and exit pipes checked for easy coolant flow.

Time for walkies.

Remove the original pump motor and compare. Grind a flat on one end of the shaft of a discarded video motor. I use the tape transport motor.
Fit the pump to the video motor using five minute epoxy. Spin the motor to settle the interface for smoothest running.
Check the coolant flow at slightly lower voltage. If it pumps 1 litre per minute then OK.
Check the pressure Head: If the pump manages to squirt much higher than the computer base to CPU height, then OK.
Pootle down to your local home brew shop or fish shop to buy some clear plastic pipes.

It is not rocket science and it gets you away from the computer screen for a few hours.

If you know the right blokes and help them out from time to time, by now you have probably scavenged an old video, stuck on an old car screen washer pump, and carefully extracted its heater matrix, and still have change from a penny.

If like many in modern Britain, you live in deprived areas, then you may often have a discarded car dumped locally which is ready to donate a screen pump and heater matrix at a price you can afford. You may also have old videos chucked on the end of the street, I do.
Happy hunting.

Warning: Always use washing up gloves, otherwise the British police may find your fingerprints or DNA and you may get 'Blunketted', even though the police should be really be chasing real criminals, not statistics. I got a clip around the earhole when I was a kid caught scrumping, and it worked.
Today, I would feel paranoid of police paperwork and social workers.
Childhood today is far too short. Kids should be allowed to be kids.
Please note: Videos are a dying technology, so get all you can as they will not be around much longer, because the DVD is now taking their place.

The CPU header.
Take a block of alloy, available from any engineering shop, possibly an engineering firm, who will have lots of odd bits which you can cut down to size. Five quid should be more than adequate for a handful of bits. Size will be the average CPU size, matchbox or as large as you can get to mount over it.
Just stroll in, and ask politely. "Hi, any chance of a block of aluminium alloy about the size of a matchbox? as I'm building a water cooled computer." They can only say no. Offer a few quid if in a poor area, or a fiver in the south east, and you may get a lot more than you expected, as the materials is simply not going to get this level of scrap value when they weight their off - cuts and swarf in for scrap. Perhaps they my give you a suitable piece for free. Just don't pester them a second time, unless it's to buy the materials on a regular basis. I have enough for another thirty machines.
If you are unlucky, then you could alternatively build a CPU header using thick brass or copper sheet and solder it with plumbers solder. If a thin piece of alloy, about 5mm, then you can build up a housing using plastic metal and brass tubes.

The larger the block, the greater the heat reservoir for smoother heat profile as it warms through. About 1/2 inch, or twelve mm thick should suffice. Of course, a block of solid silver would also be rather nice due to its coefficient of thermal conductivity, as would a block of copper, but this is happy bodge territory, not consumerism gone mad. If we all carried on like that, we could end up spending some money.

If you are spending silly money, then get a jewellery expert to craft you a copper or silver box with inlet and outlet pipes and a nice thick, solid base. The silversmith will be able to hard solder the silver into a superb piece of work. Probably cost less than a hundred quid. When working with softer metals, it is vitally important to make a structurally sound design of header. Gold has also dropped in price. To really rub in the bullshit factor, you may want to use a high alcohol content fluid, such as a real ale or larger, and perhaps you may even be able to tell sceptics that the alcohol also helps increase the thermodynamic properties under different pressure zones in the system. You won't impress me, - but the bullshit value will surely be massive and blow away the others into the last century, with their really bland, 'faster and better' catalogue tat and junk.

The CPU cooler unit is normally made from a nice block of aluminium, about half an inch thick or larger, and the size of the average cooler base, to give the unit a certain extra latent heat capacity should things fail. It could be smaller if all works perfectly, but it is far better to think bigger is better. Having a reasonable heat sink reserve before the water starts flowing or should it fail is always a very good thing.
Then down to the model shop to buy some alloy rod for plugging holes and brass tubing, choose sizes which fit the plastic connecting tubes.

The alloy CPU block is drilled with two end holes to take the brass tubing as a tight fit. These are blind holes which almost go the length of the alloy block. If in doubt, use a piece of tape on the drill at the required depth. Now drill cross holes to reach the other side, between the main holes, but again are blind holes which only connect the to main drillings, leaving just one side with open holes. Small plugs are then press fitted into the exposed holes to block them. They should be a tight fit. Using a vice will neatly make them flush.

As drilling neatly aligned holes is a pain for beginners, then start by making centre punch marks, an old nail will do. Then drill small holes, as these can be drilled larger later, especially if they do not wander from the intended path. Also drill the larger inlet and exit holes using a small drill, as there is a booby trap of drilling though the larger holes first, wail case the cross drillings to go off line. Therefore drill the many small cross holes first, then the main inlet and exit drill holes, all using a small drill bit. Then drill these holes to the required, larger diameter, the smaller holes will act as a guide. If your cross drill holes wander and cross into each other, don't worry, it just makes for a slightly more interesting cross coolant flow. Carefully clean out all holes and blow and wash clean. Dry thoroughly by warming, then plug the cross holes with alloy slugs, and / or epoxy resin or two-part, instant metal in a tube adhesive. Then clean out the tubes again, using a drill down the inlet and exit holes to clean out any excessive adhesive. Finally insert the brass inlet and exit pipes, using a snug push fit and more adhesive or instant metal. Pressure test by blowing air into the item whist underwater, as bubbles show up any small holes.

If the CPU block cannot allow the water pipes to enter from the side, then you can place them at an angle, but this will need epoxy resin or 'plastic metal in a tube' alloy plugs to fill the holes. Always make sure the brass connecting pipes have sufficient length into the CPU alloy block to support them securely. Alternatively make tightly bent brass pipes by heating, then filling them with lead or solder, bending over a soft wooden former, the melting out the solder.

Epoxy resin or 'plastic metal in a tube' the brass tubing in to the holes which should be a press fit, with the epoxy resin or 'plastic metal in a tube' there purely for extra security. Check the block fits the CPU, using an old mother board and processor if available. Now very carefully lap the CPU mating face of the block on a piece of glass, using some brass polish or other abrasive cleaner. This will give a perfectly flat and clean surface for the heat paste.
During testing, I simply give the alloy block a quick linish using old wet and dry paper and often use copper grease instead of heat transfer paste, as it is nearer and cheap, yet I still have no heat problems. My old air cooled 486DX66 used engineers copper grease and shows no heat problems after ten years. My P133 has a smear of ordinary silicone grease and still refuses to die after many years. Remember the purposes of the design and don't loose sight of the overall plan.

The CPU header and pipes can now be connected to the pump and checked for good flow through the header block. Connect up all the bits and measure into a container over a minute. If it is appreciably lower, then perhaps you have too much drag in the system and be constricted. If you have a 1 litre container and testing over the sink, then you can fill the container to check against the time taken.

It is not always possible to get hold of blocks of alloy, so one can revert to sheet brass. A simple brass box can be built and soldered. This is simple hacksaw and file work. The items are then clamped and soldered with a domestic blow lamp or butane flame, or the gas cooker.
When making, it is best to make the tubes a snug fit, then solder up the internal bracing or fins first. Then build the box, using metal clamps to hold it all together while soldering, so it all aligns easily in one solder session. If you have no spring clamps, then make a simple sets of primitive tongs from strong wires such as old welding rods and use strips of masking tape to maintain pressure while the whole unit is soldered. Tape will burn, but not before the soldering flame has managed to secure one end of the item. By making it in one session, allows for all the components to position easily for an easily aligned box. Use real plumbers solder, not the modern, awful lead free, politically correct Euro-crap.

The picture shows the side pieces are slightly larger, but this is to ensure they can be filed to shape later. Brass can be cleaned up beautifully with abrasive paper. Linishing to fit the CPU will work wonders on a box which does not look too good in its early stages.

The only brass sheet design problems are making sure the heat can transfer rapidly from the CPU to the coolant. In the example, I have built an inverted double V shape for two reasons; first to give a larger heat path from the 'hot spot' into the coolant as it passes through and secondly, more importantly, to act as an internal structural brace to ensure the pressure from the retaining spring is placed directly over the CPU. This layout does both jobs, but does not constrict the flow, yet gives much of the coolant a chance to pick up direct heat from the hot spot. Residual heat will also transfer from the rest of the box, but the main area of concern is to keep the hot spot as cool as possible.
A clip retainer using epoxy resin paste can be added later, depending upon final alignment of the header for the best position in the machine, which may be at almost any angle.

Radiators.

From experience, I always prefer the small scrap yards, where you can stroll in and tell the blokes what it is you're after and why. They rarely let you browse the arrays of radiator bits and from this, you can get almost exactly what you desire for a fiver. Normally the bloke will wander off through his shelves of stuff and come back with a couple of nearest choices. So easy and so cost effective. Recycling for fun and the environment too. Remember which car it came from, as you may want to build a few more.
Many a car heater matrix will have the pipes bent for a neat fitting in the computer. Mounting a car heater matrix is possible in many positions, but depends upon the size of the case. In small cases, the picture shows the easier positions, which simply need rectangular holes cut into the case in non structural positions which do not obstruct the rest of the internals.
Some simple positions are shown, although if the case is large, and the upper CD drive is removed then it may be possible to exit the air through the top if there is sufficient room between the lower fins and the lower CD drive to allow easy air flow. Placing the radiator to the lower rear is also possible. Mounting the radiator on the base of the case is possible if the machine is supported a short distance off the desk to allow cool airflow, but not recommended for floor mounting, in the search for the coolest air, where unfortunately dirt and dust can clog the fins.

A little radiator practice.
You will note that the picture shows that the inlet and exit pipes are all on the upper positions. It is all too easy to place the radiator pipes on the bottom of the case for a very neat internal layout. But when air gradually works its way into the system, either though the seal in the low pressure side of the pump, or from leaks, or from simply absorbing gas from the atmosphere during warm and cool cycles, then the radiator will eventuality become a big, hidden air trap. It is imperative to have at least one radiator pipe at the top, preferably the exit pipe, so no hidden air builds up in the radiator. Therefore the builder may have a problem with the car matrix. The most popular is to place the matrix on its side facing the side panel, with inlet and exit pipes at the top.
If the matrix uses brass or copper tubing, then it is possible to have both pipes at the bottom, but only if you solder a small vent pipe into the highest point, then add a small bore vent pipe to the highest point in the system, such as a small header tank or filter. If alloy, then such a vent pipe can be eposxied in position.
The car heater matrix will have pipes much larger than those used on the pump. Therefore brass pipes must be inserted to match the plastic tubing of the pump. This can be easily done by swaging the matrix pipes smaller, then gluing in the brass pipes. I use plastic metal in a tube, after roughing and cleaning the surfaces. If the holes are very large, then glue some wood onto the brass pipes and shape these into a bung which can be forced in with a little sealing epoxy.

The bare finned radiator matrix my look good, but has absolutely no mounting points, nor anywhere to fit a fan bracket. Mounting a bare finned radiator is easy peasy.
Take a piece of plywood or alloy sheet, make sure it fits perfectly in the case, possibly with rubber to reduce fan vibration noise. Smear the plate with epoxy resin and slide the fins of one side of the radiator so they build up a neat bead, then slide slightly the other way to give a perfect V mound of epoxy, thus holding all the ends of the fins securely to your mounting bracket. Use the same method to mount a plywood fan mounting plate.
If the fins are vertical, such as in the roof of the case, then you may have conductive airflow and the fan or fans may not be needed.
If you had shaped the plywood side pieces with mounting holes for the casing and for the fan(s) and such like, then your radiator is almost finished with minimal effort.
To get large fans, do not salvage old computers or servers, as these fans do not have the yellow sensor wire which can warn the motherboard of failure.
Once the radiator is positioned in the case and the plumbing perfectly neat, the front, rear or side panels can be marked. Take an angle grinder to the chosen area and gently grind out a rectangular hole slightly smaller than the radiator. Bend back all edges with a pair of pliers to maintain rigidity in a side panel, then smooth all edges. If at the front, the fins can be shaped very gently to fit in harmony with any curved front of the case.
I simply mark out the hole, then grind a big X then bend these back very carefully to allow the radiator to mount onto them, which is ideal for roof mounting. The 90 degree angle of the bends also maintain the rigidity of the panels and also offer a good mounting bracket area. Alternatively for roofs, cut Jag E type bonnet fins, which also works well for case side panels.
When done neatly, you know have something akin to a finned front or side of your case, without the need for air obstructing panels. If you have fitted your matrix in the roof of the case, always add a stand off, baffle panel to prevent obstructions entering from above. Done well, this can also keep your cuppa tea and toast a tad warmer.

The reader may now have a larger and cleaner radiator system than the small, constrictive and pitiful radiators normally found on computers. Welcome to real cooling power.
If done neatly, it should also look superb. If less than ideal, then the minimum black paint and some cardboard ducting can hide a lot of imperfection.
The mounting plate can be screwed directly to the case, or preferably with lots of double sided foam sticky pads or strip. This cuts down the noise of the fan, should it ever be needed. Fit a plywood frame to match the fan, then apply some epoxy as before, then screw the fan to the radiator matrix.
With such a nice large radiator, a larger fan is possible, but may not fit across the dimension of the radiator. In such cases I often mount the fan on an angled plywood frame and add cardboard ducting to ensure the whole of the radiator fining is part of the air flow. Some poorly designed commercial radiators have fans which obstruct part of the finning. If clever, then the ducting can be semi rigid foam which isolates the fan from drumming on the case.

Build your own radiator.

Yes, some people like the components to be sensibly proportioned for their own perfect case and therefore build their own radiator matrix. Perhaps you want to make your own radiator to fit your ideal computer case, perhaps for the next generation of 64 bit CPUs or just for a try.
It is unlikely to have to build a radiator, as cutting down almost any of a vast range of heater matrix is possible for many situations. But there are a few perfectionists out there who have not lost all their dexterity to the world of virtual reality.
I design and build custom cases and always make the occasional radiator for a total custom fit, rather than use what is available off the shelf. I have never used 'off the shelf' or catalogue junk, as I'm poor and so have far higher engineering standards.
So if you have a specific need or simply do not want to spend much money, then build your own radiator. With a little careful thought, the materials needed for a radiator need not cost more than ten pounds to build, but it will take about five to ten hours.
In some cases, just an old umbrella and a few drinks cans will suffice.

Making your own radiator is usually to fit a specific design such as the micro case, where the builder can make a high density radiator for a compact area, or perhaps to fit across the whole of the rear, as per refrigerators. These are often accompanied with a couple of axial rotary fans used to give compact, but high airflow of a hot running computer.

With the compactness of water-cooling around the CPU area, then micro cases can be liberated from the needs for plenty of room for cooling airflow, but only if designed well and the components made to fit.

Have a go at making your own custom radiator, it's not expensive and gets you away from the computer for a while.
Get some brass, steel or copper tubing of a suitable bore to the water pump pipe bore. On a small machine, then copper brake pipe can suffice. For larger capacity, then make a double row radiator. Larger bore pipe is available in model shops, or the steel fuel lines from cars. If a real cheapskate, recycle old umbrella stems, but file off the cheap chrome first if soldering and clean the insides.
The design will depend upon what is available, as not all radiators need bent tubing.
Copper is fairly easy to bend if you make up a wooden former and there are also simple hand bending tools available. For many half bends, simply make a coil of many turns of pipe around a wooden former, then slit them sideways. Filling the pipe with lead before bending helps a great deal, especially with brass and steel pipes. Then heat to melt out the lead.

Perhaps you want to make a radiator so that the fins are also the front surface of the lower front of your case. This offers easier cleaning and may add a lot of style if done really well.

For general manufacture, let's assume a mundane radiator of four inches square, or to match whatever fan unit or dual fan units you have available or perhaps to fit inside the lower front facia of the computer case. It is just as easy to make a long radiator as it is a short one, only longer tubes and more fins being needed.
Cut the pipes to length. Get some steel or alloy sheet, nice and thin. Not as thin as a cola drinks canister, unless you want the ultimate micro-fine radiator matrix. Clean the sheet to offer bare steel or alloy to the airflow and stack up plenty of sheets for a radiator matrix. Thirty or forty should suffice, perhaps more if very keen. If using cola or beer cans, then flatten them and scrub off the paint, to give bare alloy for ideal heat transfer.
As the alloy cola and beer cans are cold formed, they will be rather springy. To anneal them, rub some soap on the alloy as a heat marker then heat very, very carefully over a large, soft flame until the soap turns brown, then plunge the alloy into cold water. After this, it is much easier to shape, but being soft, will not take well to rough handling.

There are some schools of thought that believe a rough surface transports more heat, due to a turbulent 'laminar' flow, so roughing up the surfaces with rough abrasive sheet may be suitable for those wanting the best especially at low airflow speeds, where silence is golden.

Any half decent pair of scissors will easily cut this thin metal.

Warning: Drilling big holes in thin sheets is always prone to distortion and cause the object to be drilled to get out of control. Fingers can be lost. - So ALWAYS restrain the sheets firmly and always drill slowly, and very carefully. I highly recommend a good engineers vice and clamping the fine sheets between pieces of plywood.

Drill a pair of small holes into the stack of fins, at diametrically opposite corners, then use small bolts to hold them together. Clean and dress up the sheets so they are all the same shape. If you are making the fins part of the front of a sculpted case, then file them to fit any fancy external curves.
Drill holes for the pipe positions, evenly spaced along the centreline or perhaps staggered if an old hand at this game. The pipe holes must be a little smaller than the pipes which will pass through them as it is vitally important that the fins make good thermal contact with the pipes to transfer the heat. The hole in the fins must be such that the fins are firmly pressed onto the pipe(s).

Push the first fin over the pipes, then a sheet of cardboard or a few slivers of card, thick enough to space it appropriately, then the next and so on until you have a radiator matrix. In some cases, it may help to lightly taper the end of the pipe. I always make up a hundred or so thin slivers of tough plastic as spacers - a pair of scisors and an old plastic milk container.
Always make a smooth tapered end to the pipe before insertion. To keep the fins flat, use the plywood to help push them on straight without distortion.
It is NOT a good idea to make a thick sandwich of many layers of alloy or steel sheet and alternate cardboard, and then drill through them, as the cardboard allows the edges of the metal holes to grip and tear.

Once the core is made you may wish to make two larger, thicker, top and bottom or end fins which will become the mounting brackets. If these are in steel, then they can be soldered in place, or if alloy, then some epoxy resin. You may wish to make angle brackets or mounting holes in these end plates. If alloy, then these can be epoxy resined into place. If brass or steel tubes and fins, they can be soldered into place. Alternatively you can glue in some old wire coat hanger for the bracketry.

If using steel or brass fins, then after you have removed the cardboard or spacers, you can flux the lot and solder it with a gentle flame. This is rather difficult unless you solder each fin as it is assembled, or use a large, soft flame, such as a gas cooker ring after the whole assembly is built, but often not worth the effort.
If not soldering, and only using thin slips of card for spacing the fins, but the whole is a little wobbly, then remove the card slips and apply a spray coat of heat transfer engine paint, often matt black as a radiator surface. Position the fins so the paint will soak into the gaps between fins and tubes, holding it all secure once it dries, but leaving the other faces free of paint to transfer heat more directly.

To remove any cardboard spacers without damage, simply soak in water until it is all easily removed. It can take hours to remove all of it, so a few soak and squirt sessions are common. It is for this reason that I prefer slivers of plastic rather than paper to space the fins.
Where the radiator has to be trimmed to an awkward or specific shape, such as the front of a case, then the full card spacer approach keeps it all perfect during the trimming and fitting process.

You should now have a fine radiator tube and fin matrix, secured with end flanges or epoxied fin ends as mentioned later. The end pipes are sticking out, perhaps six pipes sticking out, so connecting them is the next step.
You can have the coolant flow though all the pipes in one direction if making a large bore, low pressure system or a thermo syphon design. Alternatively, the pipes can be a dual pass radiator design with the coolant going though half the pipes, then back though the lower set of pipes, so the coolant takes a longer route. If a small bore, high pressure system, you could design the headers so the coolant only passes through pairs of tubes. Never cause unnecessary constriction to the coolant flow, as the poor old pump will have to push the coolant through it. It is far better for the coolant to flow slowly across all, rather than be forced fast though every pipe, where heat transfer will be similar, but the pressure would be higher and chance of blockage will increase.

Remember how bubbles behave inside radiators and build accordingly.

The dual pass radiator does not allow the coolant to stay in the radiator longer, just faster, as the pump keeps a steady pace. The other more basic system has the same internal volume, so the coolant flows half the speed for a similar coolant heat transfer. The only advantage of the dual pass is that there is less chance for bubble entrapment due to the faster coolant flow, and the convenience of both inlet and exit pipes being on the same side for easier mounting in the computer case.
If making a single pass, then make headers for each end.
If making a dual pass, then make up a header for both ends, or some U bends to solder to the end of the pipes opposite the inlet and exit. Making a bottom header also makes for a sediment trap, but this is not needed for the short lives of home computers.
Where the pipes are close together, simply make larger bends to connect alternate pipes and gradually work both ends until the water flows through the whole lot. Unfortunately, making tight bends may not be possible, as they are not easy to do. The best way is to fill the pipe with lead or solder, allow to cool, bend carefully then heat again to remove the lead or solder.
If fitting U bends from soft copper, it is easier to make a coil around a former such as a broom handle, then slit the coil sideways. Flange out the ends of each bend to allow more solder to flow in the join and make it stronger.

Alternatively make a large header pipe which covers all the pipes. Get a larger bore pipe and drill side holes into it, then fit the pipes and solder to make a larger header pipe at each end.
The multi tube header pipe makes for easy air bubble removal, whereas contorted end bends can make removing bubbles more difficult. Adding a small vent pipe to the highest point in the radiator will allow for bubbles to be automatically removed.

It can now be pressure tested by fitting pipes and blowing into the internally dry radiator while it is under water, as bubbles show up holes far easier. Using a push bike pump can pressurise the device to over 100 psi.

Once soldered up and ready, make a couple of brackets for the fan and mounting brackets on the case, (if not mounting in foam). This is easily done by making the end fins thicker and longer.

If the radiator finning is to be part of a visible part of the system, perhaps as part of the font panel, then carefully dress, smooth and polish the radiator fins to match the machine before removing the cardboard. A cylindrical flap wheel is ideal, followed by wet and dry and metal polish.
When shaped, remove the cardboard, preferably by soaking in water until it is all easily removed. It can take hours to remove all of it, so a few soak and squirt sessions are common. It is for this reason that I prefer slivers of cardboard or nylon rather than full sheets, except when the radiator has to be trimmed to an awkward or specific shape, when the card keeps it all perfect.

The average commercial computer radiator is about 45 quid and in my opinion, too small for serious overclocking with a lightly stressed, or even passive cooling system, and certainly not so good as the various, far cheaper alternatives.

Some car radiator heater matrices are superb. I have seen a few which would make absolutely superb radiators and exactly the right width to fit into the front of a typical midi tower case. The finning of some of these items is not only fine, but wrinkled and formed such as to extract the maximum heat transfer. One matrix really was a work of art but unfortunately, no one knew from which car it came so I'll have to do some research to find this finely finned work of art.

From experience, I always prefer the small scrap yards, where you can stroll in and tell the blokes what it is you're after and why. They usually let you browse the arrays of radiator bits and from this, you can get almost exactly what you desire for a fiver. If you can make up a cardboard shape of the preferred matrix, then the bloke can wander off through his shelves of stuff and come back with a couple of nearest choices. So easy, so cost effective. Remember which car it came from, as you may want to build a few more.

If using a car heater matrix, the pipe connections may be far too big, which is not a problem, but some reducers are in order. Make a wooden or plastic bung and drill to fit the brass tubing. Note the position of the radiator matrix in the case and drill the bung in the upper side so the air bubbles will not be trapped. Then epoxy resin or 'plastic metal in a tube' the smaller brass bore tubing into place, ensuring it is water tight.
If the pipe is not too different in size, then pipe can be carefully swaged to the required diameter. If alloy, mark with soap, heat until brown, then plunge into cold water. The softer metal can then be worked with a small hammer over a small bar until reduced in diameter.

Now there's a funny thing.

Unfortunately, the fins would want to be vertical to allow for radiation. Therefore it would be best if the cooling fans in the case panels were all blowing out or all blowing in, and thus the corner finned pipe area is the only way in or out for the cooling draught.

Thus such a design, as shown here, could also lend itself towards a thermo syphon system if a large enough pipe.

You will notice that I have built the power supply (light brown) to be well inside the case, so that the air is sucked inwards over the bottom of the Coolpipe. This keeps a nice thermal incline across the pipe, cooler at the bottom.
The hot coolant rises from the CPU then the coolant cools over the lower part of the system, to return to the CPU. A pump is included, but not always needed as this is designed to be a silent and totally reliable, thermo syphoning system.
A very neat yet simple solution. Now you know why I include a copyright notice at the top and bottom of the monograph. If you are poor, then please feel free to copy such ideas for personal use only. If rich, I can build one for you for sensible money. If corporate, then licensing is available from 1,000 pounds

Companies will soon have to accept that their top of the range cases will need to include water-cooling systems as an option for the top class gamers. My extensive research in design and various manufacturing processes shows that such cases can be built for highly competitive rates and profit margins and a few for top of the range classics to promote the company's world wide image. Companies wanting interesting computer case designs are welcome for ideas. I have many.

To show how weak the market place is, a recent top case manufacturer made a stir by mounting the motherboard upside down, - not exactly radical, I've been doing it for years.

If the Western case manufacturers want to wake up, or the Eastern manufacturers want loads of ideas, then just ask. I can offer a full and wide ranging design and testing service at far better rates than the rest. This and five other radical, novel designs await the first sensible bidder.

jhpart@btinternet.com

Back to home builds.
The computer case has other options, where the pumped single radiator pipe would be ideal for a desktop case. Nevertheless, the fins need not be square, but can follow the flower designs of some fancy CPU coolers if you think you can handle making curved radiators around curves tubes. Indeed, it is also possible to carefully bend a radiator into a gentle curve, as used on many modern motorcycle radiators. Admittedly they are aluminium and not brass, but careful pressure can offer a few artistic profiles.

If your radiator has very neat finning, then there is no reason what the fins themselves could not be made into the front face of the computer case. Use your imagination.

As an engineer, I like things to be simple and effective.

As a British engineer and scientist, I have no money.

I also like stylish things.

WaterWalls. (C)

Once in everyone's life, you should come up with at least one good idea, here's my latest. It is very simple, very effective and very stylish, with many advantages over conventional radiators. This is copyright protected.
The advantages are easy build, instant coolant loss indication and instant touch sensitive heat flow assessment, silent and takes up no room when used as a clear side panel.
Again, as in many of my monographs, feel free to copy my designs, but for personal use only.
There are other types of radiator beyond finning.

If you have an aluminium side casing, then this could become a large, thin radiator, with the hot coolant entering at the top and exiting at the base. The side of the computer case has a similar surface area to a radiator, so should do quite well. Building in a second, closely riveted alloy sheet, with an integral coolant pipe along the top with a row of drain holes, and a single drain pipe at the bottom will allow a large, very thin flat radiator to be built for pennies. Sealing with 'plastic metal in a tube', then riveting it together before it sets will give a good, neat and safe design.
Applying medicinal, thermal sensitive strips from your local chemists (drug store) on the radiator, the user will have a superb temperature sensing device.

Many people want to look inside their computers and the clear side panel is now common.
Glass is not renown for radiators, but neither are processors renown for heating rooms. So do not be put off by standard thinking. Many humans have been thinking beyond soaps, football and advertising mentalities for centuries, and hopefully will continue to innovate for a more interesting future.

If using a clear side panel, then this too could become a similar design, although the heat flow though the plastic will not be as good as alloy sheet. Glass would be a far better heat transfer medium, but prone to breakage unless using good glass.

How to tell the thermal conductivity of a material? Easy: Place it in your room for an hour to achieve ambient temperature. Then see if it is then cold to the touch; It is not actually cold, but at the same temperature as the rest of the room. It merely has much higher heat flow than your finger. It is sucking the heat from your finger, and the amount of heat flow will tell you just how good it is.
(I'd love to be a technology / science teacher, to use my B.Ed and B.Sc. Gizzajob. In Britain, all that my local schools have offered after ten years, is a part time cleaner.
We can do so much better in this once fine country. I know a maths teacher doing packing in a local factory and a top programmer who is a taxi driver. Yes, we DO try to get real jobs, but being white, male and over forty is tantamount to being useless in Britain. Britain is the only country which develops stupidity as the core of management. Don't blame the kids when they then get crap teachers.)

Do not use laminated glass as this is too thick and also has a plastic centre which reduces heat flow.
Have glass cut to size at your local glass merchant. I had two sheets of glass cut to shape for three quid. Also get some specialised silicone glass adhesive, as used for various materials and common for fish tanks. I found mine in a cheap shop for a quid. Also get the spacing strips at the same time, although these will not be glass, as cutting thin glass strips is difficult, even though my local glass cutter made it look an absolute doddle. For spacing strips, an alloy strip would be far safer, and can be bent into a long rectangle to eliminate leakage problems from fewer joints. Glass rod is also possible if you know what you are doing, but harder to find. The distance between panels will be decided by the connection pipes integrated into the design. I use dowel, which in cross section, gives maximum bonding area for greater security and minimal sealant to allow me to make many for pennies.

A suitably designed clear panel radiator will allow a 'water wall' to be full of water, or to dribble the coolant on the outer face from a long upper channel. This can be made by a simple insert with a series of drain holes. A single lower drain hole will return the cooled water back to the pump. Modern chemistry has enabled there to be a variety of adhesives suitable to hold it all together.
I originally preferred bonding a small bent metal channel around the edges of mine, just to be extra safe, but when I tried taking one apart, I realised just how bloody strong the chemists have made their modern adhesives. Nice one chemists !

The upper drain channel for the water wall can be integral during assembly. Unless you are running a hot system, then the coolant will be loosing more heat than it needs to deform any plastic panels.

Although the 'waterwall' may not have a fan, it will offer a large, uncompromised and clean airflow area. It will thus allow vertical convection to flow over the surface. A natural convection current will build up in the case and any case fans should be positioned to encourage the best airflow.
Ordinary conventional radiators have their surface area in a compact, restrictive zone and need a fan to generate the airflow of constant fresh, cooler air across it. The waterwall, as does the traditional slab style household central heating radiator, uses a large, single area to transfer heat with out the need for fans. With such a large, flat area, there is no need for forcing air across the heat transfer faces as a finned radiator does. This makes the waterwall essentially a passive device, but with an active effect. Being slim, it can also be compact and thus use otherwise wasted panel areas on the machines' casing.

The fins of a traditional radiator are horizontal, so to get convection, they need to be vertical but this would mean putting the radiator either at the top to allow convection, or inside the case to prevent dirt entering. The waterwall is naturally vertical and a much cleaner design in both style and airflow.
Being passive, the waterwall often has no noise, other than the flow of the coolant through it. A cooling fan need not always be used to force air across the heat transfer area. If thermo syphoning, then this is silent and can be checked with internal flecks. With a pump, then internal flow indicators are not used, but a small visual trickle into the top of the radiator can be used, but often audible unless designed otherwise.

The picture shows one of my flush fitting waterwalls in a case with the motherboard upside down and an ATX PSU behind. It takes the place of a side pane, as I don't use side panels, but prefer glass sides to my computer cases. This one is only half filled, to reduce the heat flow as I was having trouble trying to get the system to run ABOVE 34 degrees, so gradually reduced the pump voltage and lowered the waterwall volume by half to give half the radiator area, and still this intel chip refused to get moderately warm.
The internal coolant volume does not normally affect cooling in ordinary systems, but with the waterwall, I can run it half full to halve the waterwall heat transfer area during my tests. I really like this system and it never ceases to impress. It is simply bomb proof.

If wanting a waterwall, but having a lot of heat to transfer, then simply make in glass, then add a third inner and perhaps a fourth, outer layer of polycarbonate to protect the glass. In the narrow gap between the wall and the sheets, direct airflow from a large cooling fan. Some simple cardboard ducting should suffice at the bottom, with a long, thin hot air vent at the top or on the upper sides. Sucking cool air from below and blowing it upwards, gets the best possible, by grabbing the coolest air at the base of the computer and exhausting it above the computer. With a little neat design, the warm air will never enter the inside of the case !
I now build nearly all my custom computers this way, as they are bomb proof.

Let's do a little simple arithmetic to see the values of a typical waterwall. (Not all glasses are the same.)

Q heat transferred through glass = K x area x Temp difference / thickness.

Thermal conductivity (K) = Ordinary glass can transfer heat at the rate of 1.0 W m-1 Kelvin-1 .
Heat flow of ordinary glass is 1 Watt per metre, per degree difference.
In English. That's one Watt of energy across one metre of glass per Kelvin temperature difference. In the formula, the heat flow decreases with increased thickness.

(One K=Kelvin temperature is the same as one degree Celsius, and not be confused in this equation with the K Konstant for thermal conductivity of glass.)

Therefore one of my typical waterwalls with a size of 0.25 m x 0.1m, has an area of 0.025 metres. (I can build some very small cases.)
Using a temperature gradient of five degrees difference between coolant and air and glass 3mm thick, then this works out at :-

Q = 1.0 x 0.025 x 5 / 0.003 = 40 watts per degree in temperature difference.

As the average CPU pumps out something in the region of 40 to 70 watts, then this waterwall may begin to get slightly warm by just one or two degrees above the room temperature.
Better still, the waterwall has two sides so can theoretically radiate twice the heat energy. The internal temperature of the machine is usually higher than the outside air, so the actual efficiency of the inner panel is slightly less.
I usually build slightly larger waterwalls, as I use them as the full side panels in my cases. That's why my processors never get beyond tepid. My cases can handle the hottest overclocked processors, and do so quietly, and with style.

Therefore the temperature difference is well within the needs of such machines, although the temperature can be occasionally up to ten degrees warmer than the air when overclocking in compact cases in warm rooms with no draughts.

For a simple waterwall heat sensor, I stick a cheap medical thermometer, - the type that's placed on the forehead to check for fevers. See picture. It sits perfectly well on the waterwall for a good indication of the range 30 to 40 degrees. If I ever get a computer to run above 40 degrees, I may end up using a cheap domestic mercury thermometer sealed inside the waterwall during assembly, again for mere pennies. I never expect any of my systems to ever run above 40 degrees.

See, I told you that it is the radiator that is the most important component. (No matter what shape.)
I also have some radical ideas on radiators, (but they are very patentable).

The simple, compact computer system shown opposite (series 2f micro tower) has the motherboard upside down for better cooling and a waterwall. It has shown that computers can be simple, cool, silent and very cheap to make :)

In some instances, with a little effort and careful design, with the CPU very low in the case, this system can use thermo syphoning for cooling, eliminating the need for a pump for a totally quiet and reliable cooling system. I build a few such cases and complete systems around 939 processors, to fund my motorcycle projects. Just ask, I don't charge much.

I'll stop the radiators section here, as I could drone on about radiators much more.

The point to note is that radiators can be anything.
I am sure you can now think of at least four different forms.

Well, by now you should know the basics of radiators.
The basics is that it simply is not rocket science.

Remember that it is quite easy and affordable to make your own high specification, custom computer, - if you know what you are doing.
Anything which can offer a cooling surface for heat to flow from the coolant can be effective, if sufficiently large and allows a reasonable difference in temperatures to draw heat out of the system.
By making your own radiator, or modifying a car heater matrix can ensure you get the maximum surface area for heat transfer.
You will also save money.

The other bits.

The coolant return pipe should be seen to flow into the coolant tank as a small waterfall, so the coolant can be checked. Dripping down makes a noise to guarantee a safety audible device. Flowing down a piece of clear plastic can be seen, but not heard, it's your choice.
You may have a one of those narrow, water filled 'fish tank' panels on the side of the clear panels and wish to use that as your reservoir or waterwall.

If you suffer pump shaft seal problems, then the header tank can simply have the pump mounted in the coolant, with the pressure side of the pump sending the coolant out through the top of the lid, or perhaps more neatly through a rubber grommet with a little silicone bathroom sealant for luck. A simple extension shaft can have the pump body submerged, and the video motor outside the tank. It really is that simple.

If the water pump is designed to be submerged, or you prefer it to be submerged, then it is possible to build a splash tutu around the unit, and have the motor body sticking out of the header tank using a grommet or some silicone sealant and the header tank itself can be such a size to support the pump in the lid. A suitably shaped block of open cell foam or even a bath sponge in the tank can also make a quite subtle, vibration isolating pump mounting and offer a slosh proof design without upsetting the header tank capacity.

The water pump should be 5 or 12 volts for connecting to the computers PSU or have a dedicated transformer. You may wish to use the power from your computer if it can supply the current, so check first. It is for this reason that I use a video motor, simply to prevent nasty spikes in the five volt lines for the logic circuitry.
Warning: Be very wary of fitting a 5 volt pump to the 5 volt rail of the PSU, as it delivers filtered power to the sensitive memory and other microchips. I just don't mess with it, even though it never upset any of my early motherboards or memory.

Pump design.

Making a pump is a tricky subject, as the customer wants a super high tech racing device, while a water pump system demands a slow, easy going, gentle and reliable device.
Luckily they can be cross bred to some extent to give a little enhanced character, rather than the usually boring black plastic pump.
The coolant pump is a low pressure, high volume delivery system, preferably not a high pressure system. Of course, for a computer system, this is relative, so a small pump is all that's needed. The only pressure is to overcome the 'head' of water and any restriction in the radiator or other constricting areas. Therefore types of pumps which deliver volume rather than pressure should be considered.

The pump itself can be of various designs, but the centrifugal and impeller types are most common.
The centrifugal types are those where the coolant is drawn in at the centre, to fling it outwards with vanes, to a gradually larger circular duct until it reaches the exit pipe. This the most common for garden pumps and computer water-cooling.
The impeller type is more prone to blockages, but is my preferred form from a purely engineers point of view, as it is used for jet skis and such like, to give high flow and low pressure.
Making the centrifugal impeller type of pump is best done by purchasing such a pump and doing what you can with the bits, or to build your own.

To build a centrifugal pump impeller, start by mounting a block of alloy on a decent shaft, make it the same outer profile as the typical conical units, then start the boring process of sawing slots or grinding out the vanes. Make sure the whole is balanced. Then make a casing around this, using 'plastic metal in a tube', preferably before making the vanes, so the vanes are a snug fit. The casing should be in two parts, clipped or screwed together. The metal back plate will need a seal, and it could be either a commercially available synthetic rubber seal using small O rings, or preferably two for reliability. See later.
Once the pump runs well, - see testing later - then the alloy impeller can be anodised if you wish, to prevent corrosion. See other sections of my website, as anodising can be done in a plastic cup with battery acid and a motorcycle battery charger.

To make an impeller, then a cut down propeller inside a tube is a good starting point, as they are cheap.
(The somewhat boring details on making such simple designs have been removed to save web space. It includes various tunnels for best flow and adding transparent sections and making clear casings with LED's to watch the tip streams and such like.)

Pump designs are usually boring, but not always.
The axial impeller type is the type preferred for those who will have prosthetic heart pumps in the near future. It is not used to replace the heart, but simply to allow the heart to rest, so this large muscle can recuperate. The design can be driven without any mechanical connections inside the plumbing. This would be ideal, for if it can pump blood reliably though a body, then it can pump coolant for a computer. They are also believed to be phenomenally reliable. No, don't even expect me to start getting onto this subject, as it's still expensive to make, even for British amateurs. I am researching this further for its superb possibilities, as I am sure it can be made far cheaper, but I have many other things to do too.
Send me lots of money and I will develop and build you the best. Until I have built and tested a few 'heart pump' designs, the older designs with a shaft connected to a motor as mentioned above are the preferred designs for normal case modding folk.
I have built intermediate designs, with integral components for unbelievable computer case designs, but they are seriously patentable. So I just need a job, to take out the patents. Gizzajob and I'll liven up this aspect of computer design.

The more ordinary pumps have two general types; the separate or the inclusive designs.
The inclusive has the motor submerged in the coolant, but this raises problems. It works quite well in the racing motorcycles I repair, where the pump and also the motor is submerged in the fuel. Yes, you read right; the electric motor runs in the petrol (gasoline). Even more alarming, the fuel runs through the whole of the motor to keep it cool. This is standard Japanese racing stuff, but only available on the top of the range fuel injected motorcycles. - This water pump design stuff could get sexy. This of course demands that the coolant is not electrically conductive, or not too conductive. Salt water is out, and distilled water is marginal, but possible. Even more possible if using motors without commutators. But this still leaves problems for a submerged and swamped electric motor with the bearings which would have to be nylon or HDPE bushes.

Ideally, the motor should be kept out of the coolant if using water, but it is possible to run submerged, for I have seen it happen, even with 240 volts mains AC - but never attempt this at home. I suppose you could run it in silicone fluids, perhaps even WD40, but this is expensive, and will never approach the heat transfer properties of water.
The thermal transport property of water is the best by a long way, therefore the motor should be run dry.

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The section on designing and making pumps and motors from scratch has been removed to save web space. Included modifying racing buggy motors, cobalt magnets, rewinding and shimming, ball races and making your own custom strobe lit, see-through pump body designs.
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If you are making your own pump, but do not want to have the hassle of shaft seals, and water tight bodies, then simply immerse the pump in a small reservoir. This is surprisingly easy, as the pump body can be lightly restrained in open cell bath sponge foam, surrounded with water, and free from accurate alignment and vibration problems. A short piece of piano wire shaft extending up from this can be connected to an old video transport motor using a strong rubber tube, glued and wired to connect their shafts. The video motor is similarly mounted in some semi rigid foam. The whole is assembled into a very small plastic cup or other suitable receptacle.

The advantage of a submerged pump body with external motor is that it is bomb proof. The pump is self purging and does not cause air bubbles. The container acts as a reservoir. The motor is a discrete distance from the water and remains air cooled. The assembly is almost primary school level of engineering. Adding a low water level device to the ATX power switch makes it a technically very professional piece of kit.

Build one, it should cost under a fiver and probably zero cost.
One plastic cup, shampoo bottle or similar item.
One discarded video transport motor.
An old bath sponge.
A pieces of piano wire from a model shop. This is the same diameter as the original pump shaft to fit inside the cut down screen washer pump, then a flat added to match the original shaft.
A small length of thin bore rubber tube, or if none is available, then wrap two turns of old cycle inner tube to connect the shafts.
Some thin wire to secure the rubber. An old paper clip will do.
Denser foam to mount the motor, or perhaps a couple of pieces of servo tape or double sided carpet tape.
A length of plastic pipe for the pump outlet. If wanting a neat pipe run, then exit it though the side of the cup and use some silicone sealant.
A wooden cap or lid to mount the motor. A piece of plywood or the plastic cap used to cover opened tins of cat food.
A variable voltage power supply - I use a cheap (3 quid) 3 to 12 volt mini power supply, available in any cheap shop or market stall.
Make sure the shaft is fairly short, to reduce vibration and allow the motor and pump to line up easily. the pump will then align fully in the foam when running.

Lower motor loadings.
To make an even more reliable motor, it can be voltage controlled. Pulse width control (PWM pulse width modulation) is possible but needs circuitry, as do brushless designs. But as reliability is the most important part of the design, any unnecessary circuitry is best left alone, for fear of losing the CPU and GPU.

A 50 pence power transistor and cheap variable resistor makes a simple control circuit. E.g. TIP120 series.

The simplest method of reducing the motor load is to use the pump only when needed.
To allow this, a temperature sensor is needed. To keep things even simpler, the pump control need only run the motor if the temperature reaches a certain maximum permitted temperature. This can be done with a temperature switch.
A bimetalic strip sensor and switch as this is the simplest temperature control that is possible. Scavenge this from a Japanese moped carburettor of about 1980's vintage, or from a domestic fan heater with temperature control or any of many places. Then set it up on the CPU or GPU header body to switch on at 60 degrees or whatever you desire. To ensure the bimetalic strip works correctly, it must be mounted directly with the coolant or the metal CPU block. Any external components must be insulated in a little draught free (cardboard) box to remain at the same temperature as the coolant.
Unfortunately a simple switch can make electrical spikes in the circuit, so a separate power supply is needed, preferably with a filter in the line, just to be safe.

Using thermistors controlling the TIP120 is the next stage and can be interfaced easily, but adds complexity, which decreases reliability.
For the simplest set-up, the motor runs at tick-over when all is cool, and only spins up faster when needed. During solitaire, it's on tick over. When running Far Cry, it may spin a little more often as the set temperature gets warm. Therefore I set up the motor to run happily at normal running temperatures, with the processor doing normal computing.
Then I run graphics test software, available from many websites and adjust the motor running speeds to match using a variable resistor across the TIP120 and measure the pump speed required after ten minutes on a low water volume system or twenty minutes if using a larger volume, such as a car radiator matrix. This then becomes the upper speed setting and the variable resistance measured with a multimeter and then a fixed resistor of this value is added to a thermal switch for controlling the upper motor setting.

You may think that the simplest would be to allow the motor to switch on and off under temperature control. Unless using a separate power supply, this unfortunately causes a change in background noise and may cause spikes in the circuitry, even with a filter in the motor circuit. I prefer to have the background noise of the motor running all the time and occasionally speeding up, rather than to have a stop-start noise. This also gives the motor less chance to seize should water corrode the shaft, or for water to leak down a shaft and seep into the motor, rather than fling off at the first opportunity should the seal begin to fail. Also a running motor is far easier to speed up than a stopped motor.
The motor turning over at the minimum setting, such as with a screen saver, or just word-processing, will allow a degree of backup should the system fail elsewhere, plus any pulser from the motor will not alert the fan sensor on the motherboard.

At the end of the day, it is up to personal preference whether the designer wants the motor on/off or variable speed or whatever. More on this may be added at a later date if requested.

Ideally the temperature sensor would be a thermistor in the CPU header or stuck with a dab of glue in the gap under the heat sink and very close to the silicon die. This would control the motor and coolant flow, to maintain the ideal running temperature with minimal power use and maximum reliability and minimum temperature change in the expensive silicon. I often embed a couple of thermistors in my CPU headers, but they require electronics and this means potential problems. They can be connected to the secondary motherboard temperature sensor, as used for case temperature, or connected to a simple LCD temperature sensor display.
I prefer not to use a variable resistor as they can corrode or fail. I always replace with a fixed value resistor after testing.

If you can interface a motherboard temperature sensor, then this could be run through software, but who trusts software this much? I certainly don't want my cooling system stopping every time I get the dreaded blue screen of death. (The long suffering Royal Navy is soon to have new destroyers using Windows 2000 to control its defence systems and missile controls. - The mind boggles. God save us all from Blair and Browns so-called 'cost effective' government economy management. I would far prefer to put my life in the hands of a Linux system. The new Royal Navy aircraft carriers are a French design. Nelson would surely condemn New Labour for treason. Please, please, please vote to keep assholes and lawyers out of politics and a Navy to be proud of.)
(Check out Flightlinux.gfsc.nasa.gov for details of spacecraft control systems.)

Greater reliability = less componentry.
The above has mentioned dedicated pumps, where the pump is an integral part of the system.

I don't like the thought of having any system at the mercy of a pump. I much prefer to have the system self sustaining, even should the pump fail.
The pump design I prefer is the semi passive form and is the type I now employ in all my computer systems.

The problem with semi passive forms of pumps is that they need specific radiators. As I build my own, I have the advantage of designing all my systems from the ground up. I enjoy ATX motherboards in the BTX style, ultra compact mini towers with waterwalls and large radiators which allows me to remove the pump, ideal for thermo syphon designs. I use much larger radiators than the piddly little excuses used in commercial designs.

For such machines, I use a thermo syphon system and use a dual flow for the CPU and GPU, so that two streams can be used with a single Waterwall or Coolpipe(c). These have separate pipes to the processors, but can use the same waterwall.
It is the heat in the water above the individual processors which control the coolant flow, so each processor is temperature controlled by its inherent nature, without any assistance whatsoever. This is another reason I like running my processors with direct cooling and no CPU header block :)

Once the system runs happily, only then do I add the pump to act in concert with a temperature sensor. The pump only works in a secondary manner to impart greater flow to the system if needed. The pump is only needed if the GPU needs a little helping hand when the coolant begins to get warmish or the flow is not adequate. The problem of course as you will know, is that the GPU is poorly positioned, so thermal flow is less than ideal. Although reasonable coolant flow is possible, the GPU cannot guarantee fast enough flow in all graphics tests. Therefore a little GPU help may be needed, and so a semi passive pump is recommended.
A semi passive pump can take two positions, either on the heat riser pipe or in the return cooler flow. If you have a hot CPU and wish to actively cool both, then you may wish to put the pump in the return, so it encourages flow to both.
The semi passive pump is simply added to the chosen line, then pumps its outlet via a nozzle in the coolant line to speed up the coolant flow. Little pressure is needed, as any half decent thermo syphon system must always be extremely free flowing and well behaved. This makes a very quiet and inherently safe system.
My latest semi passive systems have greatly improved the component design for extremely compact systems, as I now integrate my pump designs as part of my various forms of radiators.

Personal pump design considerations.
The top computer cooling system components I have seen appall me, as they are poorly designed, badly made and highly constricted in their coolant flow. Even the top memory coolers have silly adhesive labels which simply reduce the heat transfer properties. - It really is not good enough. It is not as if this stuff is particularly difficult to get right, as it's very basic engineering.
Although for the money paid, many commercial pumps are reasonable, much of the rest of the components are usually awful in design, materials and build quality. Although the pump motors are not so well made as video transport motors.

For me, if a job is worth doing, then it's worth doing properly.
In modern Britain, this invariably means doing it yourself.

The point to note is that there are many ways to make your pump, but to be quite frank, it ain't worth the hassle unless you are a model engineer. But done well, it can be like much of the engineering world - a work of art.
If a chap can build a working model of a Napier Deltic engine, then the rest of us can do something moderate. If you don't know what a Napier Deltic engine is like, then make sure you check it out on the internet, - it will do your head in.

For those who want fancy motors, then the racing buggy motors can be 'enhanced' - that is to say, detuned for use in a custom computer system. Softer brush springs and larger gaps between armature and magnets for a softer drive. The motor and pump can be a work of art, using commonly available components and in a far more interesting manner than those bought 'off the page'.
But the bottom line of making your own pump is - don't bother unless you want the best. Decent levels of water-cooling cannot be bought off the page.

Always remember that the water is a transport medium and it is the flow that counts, not the pressure. The heat transfer properties of the water can only transport so much heat, dependant upon the difference in temperatures between the block and the coolant. A small bore system flowing fast can carry the same heat as a slow, larger bore system.
Doubling the cross sectional area of the pipes needs only a thirty percent larger diameter pipe. Therefore I prefer a slow, lazy pump which transports ample water around the system, rather than a small bore system which needs high pressure to pass enough water to cool the system. This gives the builder a far greater ability to increase the coolant flow for later and probably hotter chipsets, or to add CPU, GPU, memory and if fitted, a north bridge cooling system.
I personally like to position the radiator and CPU header on a similar level, to finally reduce the need for any pressure to overcome the slight height. A truly under stressed motor and a low pressure system is far less likely to leak and is what I consider a reliable design. Should hotter chips arrive, then this system will be ready and waiting. No need for a stronger motor, a second bank to the radiator or a different CPU header mounting device.

PSU and north bridge - perhaps a second pump and a dual flow radiator to allow the hard drives and north bridge to be cooled. There are no limits to water-cooling. Perhaps you want to go further, water-cooling the memory and power supply too, but the convoluted pipework and height differences prevents this from running happily without a pump. Unless there is a good reason, then don't.

In these days of 600 watt power supplies and rumours of intel dual processor CPU's and GPU's needing 120 watts apiece, then the future looks daunting or challenging, depending upon your viewpoint.
I'm an optimist who likes a challenge.

You may want to water-cool the PSU main power control chips which are mounted on the alloy finned heat sinks. This will probably need replacing with brass or aluminium alloy heat sinks to fit into the printed circuit board in the same manner, or have water jackets built around them.
An easier manner is to simply epoxy a water channel around the PSU alloy fins or to bolt a heat sink to them, with thermal paste of course. A little tin box will do. Once again, the coolant flow must be across all of them, for fear of separate flows causing uneven cooling.
Don't forget to add cooling fins to the capacitors.
If water-cooling the power supply, always have the coolant header pipes easily removable and the outlet pipes from the CPU as inlet and exit pipes soldered through the PSU casing. This is simply for convenience when building. I prefer to drill a couple of holes in the PSU casing and solder a pair of through - pipes for inlet and exit in the side of the PSU casing, so the internal plumbing of the PSU remains modular. This allows fast swapping - out of a PSU with ease for modding or changing at your convenience.
Position the PSU pipes so that it can be mounted vertically or horizontally, so always design and check for no bubble entrapment by making the exit pipe higher than the headers, as this can be very difficult. Therefore placing the bulkhead pipes high in the PSU will help remove bubbles for the PSU and can be easily seen. The height difference makes this particularly problematic, and the reason why my PSU's are mounted on the base of my custom cases. This also allows a nice, clean airflow in the cases for an open, warm riser area in the case, far away from the electronics for a much cooler running case.
I still suspect watercooled PSU's mounted in the normal manner, which are now coming onto the market, as they are surely prone to air entrapment. I also dislike having the PSU with just coolers on the chips. As the PSU had large flat panels, it is asking for a thin wall of steel to give a nice, large cooling panel on the side of the PSU case, with the coolant being cooled even before leaving the PSU, or as a separate, sealed PSU only cooling system.

As you may have guessed, there remains a vast waste of design opportunities in the computer world.

Putting it all together.

A full tower is not necessary, as most computers have loads of room on the base. I saw my first full tower on a 386 and thought it a joke even then. My mind has not changed over two decades and I consider something like the Antex Aria as a far better design for modern computers as the heat from even the hottest processor is NOT a problem if done well. Many of my systems run in micro ATX cases, or small custom cases, and run very cool indeed.

The main problems with the radiator is making sure the cool air flow can get through. If you want a clean case, free of excessive dust build up, then the radiator unit can be surrounded from the rest of the innards using corn flakes packets with masking tape, with only the pipework and fan leads passing through. Make sure there is plenty of airflow for the radiator. This can also keep the rest of the computer even cooler.

The advantage of water-cooling is that there is a far more gradual heat build up as the water gets hotter far slower, allowing a few more minutes should it fail, before cooking compared to a fan system. A water cooled system will take longer for the temperature to settle down.
Do not be in a rush to reach conclusions. Keep an eye on the whole system for a month as it's pushed further and probably overclocked. Adding a little antifreeze may be of help if you run it outdoors in the Arctic, but otherwise, it's only good for UV fluorescing, along with all the other neon tubes and lighting malarkey.

You can pay 60 quid for a large pump and small radiator, or build a sensible pump and much better radiator.

Pump 6 quid, brass header 5 quid, piping 2 quid, radiator 5 quid, fan 4 quid and another fiver for bits and pieces = 20 quid max. About the same as a cheap water-cooling kit, but with far higher specification and ability.
Easy peasy. :)

Finally, the reader may be asking what my cooling system looks like.
This month it's evolving from an active waterwall towards two main types, - the semi active thermo syphon waterwall with pump in an auxiliary mode, - and another design which I do not wish to mention quite yet. Both are super silent and take up little room, use direct external air without passing through the case for maximum cooling, very cool internals and are very cheap to make.

To help a poor British engineer on the dole, you can buy one of my designs. I sell a fully tested and overclocked, quiet, polished mahogany case with tinted glass waterwall sides, designer system built to your specs and overall size requirements with X800 and Far Cry, flight sim, etc, dual DVDRW, full wireless network optimisation, matching keyboard and mouse from about 1000 pounds. I will of course need to test it fully for a week before being fully satisfied :)
The system would be Raided, lightly overclocked, run cool and quiet and be optimised with Tweak XP and many other means to make it run faster than anything else on the planet and bomb proofed. Plus a years access to my phone number.

They are merely steps towards the ultimate water-cooling system. Once I get a job and can afford to spend real money on what I need, then watch this space. Gizzajob.

The CPU is passive with thermo syphon cooling. No pump is used for the CPU. For games, the GPU has direct water, semi active pump cooling, with a tick over mode, plus games causing higher pump speeds with temperature sensor feedback. This feeds into the same waterwall as the CPU. There are no fans apart from the PSU and the motherboard memory has a small fan working from the 'fan1' socket and a little ducting, along with memory cooling. The motherboard is mounted upside down, BTX style. The PSU is not water-cooled being quite happy to run cool in the bottom of the case, allowing the upper half of the case to be a large void for heat exit flow through the full radial venting.
The next step is to have sealed, passive internal PSU water-cooling, to reduce the need to one small PSU fan.
The case is mahogany stained wood with a tinted glass front with no visible buttons, edge lighting for power and HDD. The sides of the case are glass, one side being the waterwall. The other glass side is simply slid in place for easy access. Cool air enters from the base of both sides, to give a clear, cool passive flow up inside the waterwall and across the back of the motherboard. The top is glass and the warmest area, ideal for keeping a cuppa warm, with large air vent around all sides, but cannot allow pens or other items to enter.

I will soon be building my whole motherboard with direct cooling of the CPU, GPU and memory. No heat sinks. By building the water-cooling directly on the assembled motherboard, the system is dedicated and the motherboard simply has two pipes coming from it. This allows the whole to be mounted and removed easily. The CPU is totally committed to water-cooling and has long pipes bonded directly to it and positioned so they make excellent and neat plumbing for the cool downer to the bottom of the motherboard and a hot riser to the top. It also allows very neat piping which is restrained using one of the spare edge mounting holes in the motherboard.

As you have read this far, the I hope I've shown you that the best is easily obtainable.
With some fairly basic engineering skills, you can make your dream system for next to nothing.

I have built many systems over the last ten years, often for customers who want their own custom systems. I enjoy this and gladly pass on the information for all to enjoy.

The main advantage I have learnt is not in buying commercial items, but in designing a decent case first, so many of the main problems are eliminated before they occur. The above pictures show a waterwall with low mounted PSU and my compact 'nano' tower system. It cost less then fifteen quid to build the case and water-cooling system but many hours in design and building, as good design, glass cutting and decent mortise and tennon joints don't happen easily.
I'm about half way through my development process and it's been a doodle to date. See also my website for case design.

Well, there you have it: - Yarbles to fancy coolant pumps !
The pump can be pitiful, yet still be run at less than full speed. Fancy pumps are not so important as many think.

Far better, nicer, truly effective and a wide range of radiators is possible.

You can buy a CPU header if you must, or look out for a small block of aluminium. Save your pennies, - about 4 quid should be enough.

Teaching:
(If I ever get offered a job teaching technology one day, and I live in hope with my B.Ed and B.Sc, then one of my projects would be computer case design and innovation for 14 year olds.
The lesson plans, handouts, materials lists, dimensions and methods and the overall aims and objectives, environmental implications, ergonomics, styling and social malarkey and also the fun aspects to develop young minds to think for themselves have been written and available for a low fee of 25 per set, which allows the teacher to print out the hand outs ad infinitum for their own use. Extra items such as heat transfer experiments and soldering kits and lessons are also available for an additional fee.
I always add a fun aspect for each of my lessons, as modern British kids have low attention spans due to TV and have disrespect for our modern education system. The teacher should be there to help the kids blossom, not oppress them through an examination focused system.
Passing exams is NOT the same as learning. We can but live in hope of better and more enlightened government and much happier kids.)

Fridges. The art of lack of pennies.

Just because you are running your processor below freezing does not make it run faster, A heavily overclocked processor can still run in a stable manner at about 30 degrees. What is important is that the heat is removed to allow it to run in a stable and reliable manner.

But some people may want to play the numbers game. Unfortunately they do not always understand the numbers they use. Nevertheless, here is a little taster of the knowledge I am building various systems upon.
I'm a poor Brit, like so many thousands today, with B.Ed, B.Sc, and even more poor sods with loads of other useless qualifications and a high university debt. Gizzajob.
Please give British jobs to British people before giving them to immigrants, as increasing thousands of Brits are getting more than just a little pissed off with having the abilities, but not the chance to use them ! Political correctness should never have been allowed to alienate native Anglo Saxon folk. I'm simply fed up with the plague of political correctness that is now stomping all over those with the ability to do the job.
Whatever your nationality - Be proud of your country - so live there and try to make it better.

Like increasing numbers of native Britons in a divided country, being poor does not mean you have to accept second best. In many cases it means you can have far, far better than the catalogue junk now abundant in this country with a proud engineering history left far behind it.

You're probably not surprised that I've gone beyond water yonks ago and now designing refrigerant systems which easily fit in my micro tower. But that's another story, as being unemployed with a B.Sc, HNC in refrigeration, and loads of other quals, but in Britain, I'm having to save up the money to take out a couple of patents. (Gizzajob) Total cost of this true refrigerator system is about sixty quid, plus some very clever low cost design and engineering. Probably a commercial design for mass production cost about ten to fifteen at the factory door. You just would not believe what parts I am using to give total reliability, looking to get a steady minus five degrees on a fast using a system which fits easily in a standard CD case. Condensation is my biggest problem, but that's another clever and lateral piece of thinking.

If I can remember anything from my HNC refrigeration college days, the phase change may sound exciting, but merely a means changing from a liquid to a vapour. (It also has similar meanings for heat treatment of austenitic metals and stuff, but that's a metallurgy story which I did elsewhere, yawn.)

Refrigerant theory.
As you will know, it's difficult to get the water below the room temperature.
Refrigerants have a trick.
The first trick is to make the difference between room and the refrigerant much HIGHER, so that lots more heat is removed from the system, even on a warm day. To make the greater difference in heat, the refrigerant is compressed, and according to PV/T=PV/T=MR, the compressing makes it hotter. Being hotter, it can then remove a lot of energy from the refrigerant and is then cooled close to room temperature.
Then this compressed, room temperature refigerant is decompressed, allowing it to drop in temperature, way below that of room temperature.
So all you need is a pump, a radiator and phase change unit, which is just a decompression valve.
Changing from a compressed liquid into a vapour, by releasing it though a nozzle into a low pressure regime, means that it needs to absorb heat to vibrate the atoms faster for the larger volume it occupies. It becomes receptive to absorbing heat.
It is for such reasons that refrigerants are designed to sit nicely on the very limits between liquid and vapour at room temperatures. The old 'Freon'(tm) and CFC families of refrigerants and even earlier ammonia, are probably the best known, but have led to depletion of the ozone layer. Because of the very nature of refrigerants, they remain volatile and problematic, although they are getting less dangerous.

The system compresses the refrigerant in a pump, so it gets hotter. This is then run through a radiator back down to room temperature. It is then pushed through a nozzle into a larger area at lower pressure, thereby reducing its temperature. When done over a hot item when reducing pressure and turning to a vapour it can cool to below room temperature. Then the expanded, warming vapour drains down to the sump. From the sump it is compressed and runs through the cycle gain, thereby extracting heat from the hot spot and pumping it out via the radiator.

Look at the back of a refrigerator and you will see the pump as a big, sealed black tin at the bottom, which has the pump running in the liquid refrigerant for simplicity and reliability. Follow this up to the large flat radiator and then to the phase change unit, usually attached to the large cooling plates at the top of the freezer box, then back down to the sump again.

Warning: Do not open the pipe system, as it may contain politically incorrect refrigerant. These are the less dangerous successors to the earlier 'Freons', the CFC chloro fluro carbons. You may unknowingly become an Euro criminal and enemy of New Labours henchmen and henchwomen.
To restrain the system, crimp or seal and cut the pipes so you can work on discrete sections. If you wish, you can run the coolant from the pump and run it into a metal container, then seal and keep for later experiments. But don't tell Blunkett or his police state Gestapo.
There are 25 million fridges scrapped each year in Britain, so you may want to do your bit in the recycling for a better environment.
If you want a vacuum pump for vacuum curing composites, the fridge pump is ideal. See my website for carbon fibre manufacturing at home, Yes, I build a few carbon fibre computer cases.

At this point, you are probably ready to grab an old fridge, pliers and soldering iron. But you do not have to think like every other average Joe. Perhaps you still retain some imagination after playing computer games.
You can try to focus beyond the screen.

Everyone seems to want to get just their CPU down to the lowest temperature, then brag about it. Cooling is not a numbers game. It's a holistic game.
The CPU is not the only chip in the game, it just happens to generate heat more and run hotter than most, but not all chips, especially some sound cards. The GPU and memory may also need cooling. My DVD burner also gets hot.

Therefore the reader should take one step back and look at the whole game. Hot hard drives and such like all add to an unreliable system when pushed hard. It may be preferable for many in hot countries to consider cooling the whole machine.

You have probably heard the jokes about running the computer in the refrigerator, but it need not be a joke, if the whole of the computer becomes a refrigerator.
Pretend you are rebuilding a very small fridge, which just happens to be in an old ATX case, then just happen to put a computer inside, and the ice box over the CPU or beside the CPU fan. What have you to loose. If it does not work first time, then no worries, you are on just another learning curve to overclocking paradise.
In a very low heat regime, even the humble ordinary air CPU cooler can work at lower temperatures. Even keeping it close to zero rather than below, will reduce condensation and ice problems. It is not as if any ice building up on the CPU cooler fins would be considered a problem !

If you have the case becoming a fridge, it is best to consider the WHOLE scheme. When building your own system, it would seem obvious to freeze the GPU and GPU. This can lead to cold spots inside the machine. If done properly, the heat removal can be kept almost totally outside the case. The inside of the case merely a cool box containing the CPU, GPU, hard drives, burners and such like in a cooler regime. The radiator kept totally external.
The CPU and GPU coolers will not just be cooling the two chips, but the whole of the inside. Only a fool would want to have fans drawing warmer temperature room air through this type of design. The only fans inside would be used to keep the cooler air flowing gently where needed, such as over the memory and recycling around the hotter CD and hard drives.
As cases are easy to seal, as they don't have to be air tight, then going for a cold internals seems a good move. The average refrigerator does not have to work with 200 watts of heat, but with an improved radiator with active cooling fans, this is roughly possible with a constant running pump. At least it will be a lot cooler than normal systems.
The phase change on a typical refigerator is mounted to the metalplates of the ice box and these can simply be used to be in the general airflow inside the insulated case.

Because of its ducted air system, the power supply unit will also use only the airflow inside the case. Cooling the PSU is not really necessary and cooling the PSU is of little help, when the system needs to keep all its refrigeration power inside the case. So alternatively the PSU can be ducted to use only the external room air, so must be ducted and insulated from the internals.
I use a piece of cardboard ducting to isolate the PSU internal fan to vent up to the outside of the case, through Jag E-type slots again. This way the PSU is an external device, but sits inside the case for neatness. A few layers of cardbaord, painted to prevent going soggy is all I nedd to keep the cold inside the case. (To be thermodynamically correct, - to keep the heat out of the case.)

The actual working calculations will depend upon the power of the refrigeration unit when placed in the case, if it runs below room temperature on the outside of the phase change unit, then a fan can blow air around the whole system. If the internals remain below room temperature, then there is no point in ducting room air into the system case, as the external radiator will do the job of heat removal.

Primary tests.
If the enclosed system brings the system ABOVE room temperature, then this will mean that the whole case as a cool box is not worth bothering about and you must resort to localised cooling of individual components.

The builder will have to either read the manual and specification of the donor refrigerator. If the heat generated in the computer comes close to the heat removal of the refrigerator, then the builder will have to make modifications.
The first and simplest upgrade is to vastly improve the refrigerator radiator, to make it compact and more heavily finned, plus a long, snaking pipe to allow the refrigerant to cool faster. If the piping in the radiator is doubled, then twice the heat can be removed. Adding an active fan to help remove the heat from such a compact unit will also help. The pump will still be working as intended, but unlike a fridge with occasional pumping session, may be running more often. Some pump control mods would be needed for a more sophisticated system, but at this stage, the builder is simply seeing if the primary system will make a suitable test rig.

If using a working refrigerator, then simply fit two or three 100 watt lamps inside and see if the various standard or fast cool settings work to keep the internal temperature below freezing.

If happy with the possibilities, then gut a refrigerator, trying to keep all pipework intact. If you must dissemble then always crimp the pipes before cutting. Place the big black pump unit on the floor, then a couple of hoses to a radiator and a CPU cooler which has the phase shift valve. This will allow the cool, pressurised liquid state of the refrigerant to expand and drop its temperature across the CPU and thus freeze the area. The resulting low pressure vapour will carry away excess heat and return to condense, then be pumped back around the system. The problem of course, is to keep all refrigerant inside, and if not, then get the system safely filled with refrigerant, while also keeping the system compact.
Remember that fridges are not known for having a couple of 100 watt heaters inside trying to spoil the plot, so expect it to run more than a typical fridge which usually has passive components, - dead meat and vegetables, - not some CPU's, HDD and stuff buzzing away inside.

Five years ago (1998) I developed such a compact system and can offer a far more refined, true refrigeration system which happily fits in a 5-1/4 inch drive bay, if I can get financial help to take out my patents, I can start building them ten at a time for about 40 quid to build, and 80 quid to sell. (Gizzajob or support to make my first million.)

A fridge is a bit like a rather large computer case. A full tower has loads of spare room inside and nice flat sides to take the external radiator of a small fridge. Cutting down fridge components and soldering them back together is not exactly rocket science.
In this case, I prefer the full tower, as it allows plenty of room for the fridge pump, and the motherboard is half way up the case, where the chilled air is allowed to flow down to any icy areas and any damp warm air is allowed to the top section. I make sure the whole system is free from damp air before sealing and a hair dryer and silica gel is also used prior to sealing. Sealing is not perfect as the DVDRW will have gaps, so I make sure it is boxed in enough to eliminate most of the air gaps, but still have its belly open to the cool internals. The hard drives have no problems, being fully airtight. Silicone spray is used on any exposed circuitry which is not already lacquered by the manufacturer.

The builder will have to make many mods to the case, so I use an old beige box as my starting point. The PSU is isolated by using tin plate angled ducting to the outside, usually to the upper face of the case in a small case, or to the outside just below the PSU, so no airflow reaches the inside of the computer. This is then insulated with cardboard.
Then the problem of making an external radiator system. This can be finned device with ducted airflow, possibly using the whole side of a case, by making a thin radiator on the unused side of the case, then covering with a flat panel. I have other ideas for more efficient systems, but they are not fully proven at this stage.
Then comes the process of plumbing it all in. This is much nicer than one would think, - the metal pipes are small bore and easily bent to make supremely neat plumbing. The pump is then mounted where possible in the base and always on rubber mounts. Always fit a few coils or S bends in the pipes to the pump unit to allow for vibration resilient connections. Once the case internals are about right, the system can be run without the motherboard or internals, but with a couple of 100 watt lamps, just to check it actually works, or is in need of more work.

The gutting of a refrigerator is not a politically correct process and the refrigerant can be lost due to evaporation. so it is vitally important to work outdoors and retain all refrigerant. In the worst case, simply crimp off the pipes to the pump unit, which is also the reservoir. Then only resolder on the pipes at the last moment, once the phase change unit and radiator has been built. I use a brass outer sleeve to join the pipes, then simply solder them.
The system has a metal pipe to the radiator, which should be rebuilt using many more fins and preferably retain the original length of pipework. Radiators are mentioned in the water-cooling section, but in this situation, simply soldering on masses of steel fins to make a large flat panels which can take a ducted fan is recommended. Always have the coolest room air flowing over the exit of the radiator pipe to ensure the maximum cooling effect. I prefer the exit of the radiator at the bottom, with the hot at the top, to encourage thermal air flow which can reduce the need of the radiator cooling fan.
If soldering many fins is a pain, then simply slide many fins over the last few feet of the radiator exit pipe. The rest of the radiator pipework can have simpler finning as it runs warmer and dissipates heat a little easier.

Unless an engineer, then the phase change unit must be carefully removed and kept intact, with plenty of pipe to prevent heat damage when soldering it in place. It takes the form of a pressure release unit into a larger volume to absorb the heat. For basic designs, simply keep the freezer plate intact and mount in the open space in the case.
If just cooling the CPU of a non sealed case, then solder or clamp on a flat copper plate to mount on the CPU. A second item can be used from another refrigerator for the GPU, perhaps with an added copper heat path plate to mount on the graphics memory.
The biggest hassle is the piping to and from these items. Flexible pipes using PTFE linings, such as the small bore aramid motorcycle brake lines can be used, but they will need the special end pieces, and their mating connections soldered to the refrigerant pipes. If this is too much hassle, then simply use copper brake pipes for cars which can be easily bent to shape. Adding three or four turns of a coil into the pipe makes it far more flexible and reduces strain on any mountings and thus allow the CPU to be removed.
To make good soldered joins, swage the ends of one pipe to make a flanged end and file the other pipe to a mating chamfer. This makes a little circular cup around the join for extra physical strength. Sleeving is also a good way and is preferred.
A little thought goes a long way, so if you have built your motherboard with the phase change units in place, with associated pipes, then it could be fitted into place, with perfect alignment to soldered or banjo connections to the rest of the system which are easily fitted with minimal hassle.
My biggest problem is finding small closing valves to the pump, so that my systems can be modified many times without loosing too much refrigerant during development. In the end, flexible pipes are recommended for many changes using a sealed system.
If you wish, you can now run the system, or get a refrigeration engineer to top up your system first if you think you lost too much refrigerant. But have a try first, as you have nothing to loose. To assess below ambient temperatures, then a digital or traditional thermometer can be used on the bare system then the normal bios checks for temperature can be run to make sure all is well when working.

If you are keen, you can attempt to make a more compact pump box, but remember that this is a pressurised system, so flat sides are not ideal. Building a long tube over the pump and motor is probably a better solution for most people. Always include the recharging valves and ensure the power lead remains perfect.

When happy, the whole case can then be insulated to reduce condensation from the water laden room air. If the case is sealed, then the moisture in the case will soon condense and remain away from the components. To prevent he moisture condensing on the CPU and GPU blocks, then these can be covered in their own little egg box. The memory and other chips will be warm, so the moisture should remain clear of these. There are many moisture absorbing silica crystal packs available for absorbing any moisture when the system is built and sealed. If wanting a clear panel, then purchase some anti misting polish for the inside of the panel, or use double glazing.

The humble egg box vs condensation. - If you are not sealing the case, but merely freezing the CPU or GPU, then condensation will occur. This can cause ice on the processor and possibly damage the silicon through physical damage. It is important to prevent this by keeping any damp air away from the processors.
Mix up lots of egg boxes and include a few finely shredded pieces of cotton to help make a stronger mix when it dries out. Cover the CPU and GPU in food cling film then apply the paper mache until it dries out. Make up light, thick cardboard pulp panels and once dry, lacquer them to prevent them turning to mush if condensation occurs. Apply the CPU and GPU insulating panels with small pieces of double sided adhesive tape, which also imparts a small air gap for even more insulation. The various gaps can now be filled with more pulp and allowed to dry. If insulating the GPU and GPI, then cover in food cling film and simply mould the heat shield over them for a snug fit with no room for frozen air to accumulate.
The computer internals can now be added and tested. If all is well, then the system may work really well, or may be a complete waste of time if the internal case temperature rises above room temperature. But in most cases, it will be far nicer than a standard refrigerated system, and at the worst, can simply be de-insulated and fans replaced for internal cooling while retaining the CPU and GPU refrigeration units, or if it struggles, then just the CPU or GPU cooler.

Total cost, about nothing, just some solder and egg cartons. So next time your fridge has a cracked its plastic inner panels and due for disposal, then start crimping the pipes and remove the bits. Don't forget to take out the thermostat, controls and also the plastic strip magnets in the door seals.

It's not rocket science, so have fun. :)

John Partridge.

Gizzajob - pleeeese !

As mentioned earlier, real engineering is doing for a fiver, what it takes a big corporation to do for a thousand quid.

The biggest problem is finding the bits. This is an art in itself and mentioned in other articles on my website. But when you get to know how to tackle scrapyarding or 'dumpster engineering' then you can create almost anything. (Many British schools technology departments are now often run on recycled engineering - when they can find a decent teacher who can scavenge to degree level.
I'm sitting on my arse writing webpages, when I want to be teaching technology in secondary schools. - So please, please, please Gizzajob ! )

Some useful sources.

An old video recorder should supply at least two pump motors. A third motor can be used for front panel transport if making a hidden computer front facia. Some LEDs and small switches for computer front panels and some metal plate for brackets. Try to keep the motor rubber mounts and their metal brackets for quieter water pump mountings. If going to phase change CPU freezing, then also check out that moisture sensor in the video.

A scrapped car - for heater matrix and screen washers, plus some plastic tubing. 12 volt relays and some wiring.

Temperature monitor at www.hmonitor.com
Fan speed sensor at http://www.almico.com/speedfan.php
Calculator at http://www.joshmadison.com/software
Electric and other parts from maplin www.maplin.co.uk
Powerstrip for overclocking your graphics card.

Always have a go yourself, it really is not rocket science.

Have a nice, cool day :)
John Partridge.

The author can be contacted via
jhpart@btinternet.com

My website has stuff on building your own computer and interfacing computers to make your own stuff such as full size wind tunnels at home. Plus lots of other interesting stuff too, such as fixing a tap !

This monograph only stays on the website if I get enough email replies. Those with the fewest replies get dumped to make way for others. So if you liked this monograph, email and offer any advice or things you would like added, so that I can make it more useful to all. It's a Darwinian process which seems to work well for the benefit of all. This one is getting close to being dumped.

Update:

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Mahogany and glass custom sized ATX and BTX cases from 250 pounds.

Mini tower or desktop cases with your choice of motherboard, processor and PSU from 500 pounds.

A fully tested and overclocked, super quiet, polished mahogany case with tinted glass waterwall sides, designer system built to your overall size requirements with super GPU dual DVDRW, full wireless network optimisation, matching keyboard and mouse from 1,100 pounds.
Fully installed from 1500 quid, mainland England with 2 yr support and repair.
Tinted glass computer desks from 500 pounds.
Truly ergonomic gaming seats with electrically adjustable squab and lumbar, in a variety of custom designs from 220 pounds.
Seriously complete, all glass computer suites with computer from 2,500 pounds.

I build only four exclusive systems a year, three for customers. The profits pay for the fourth machine for me.

Lawyer stuff. Always try to improve society rather than just take from it. Until then, lawyer stuff. Those using this information do so entirely at their own risk. Errors and omissions excepted. Contents subject to change without notice. All material herein is subject to copyright, patent and other intellectual property rights. All rights reserved. Copyright (C) J.Partridge. 2004. Have a nice day:)