Cathar's water cooling resource and FAQ
This document intends to provide some information about water cooling your computer, and is meant to be useful for both beginners and experienced water coolers alike. This is a "living" document and will be edited and updated by me (Cathar) with new suggestions and extra information as time goes by.
SECTION ONE : INTRODUCTION
1.1 What is Water (Liquid) Cooling?
Water cooling refers to using a liquid (usually water) to remove heat from hot components in a computer and move that heat to somewhere else where it can be cooled more efficiently when compared to using a socket or slot mounted air-based heatsink.
Water is the most common liquid that is used in liquid-cooling setups (hence the term "Water Cooling"), although it is not the only liquid which may be used. Throughout this document I will often use the words liquid and water and interchange them, except for where I will specifically describe an alternate liquid to water.
1.2 Why water cool?
Water is many times more efficient at conducting heat than air. It is able to absorb substantial amounts of heat without rising in temperature greatly (compared to air) and this makes it suitable for absorbing and moving heat away from very hot objects to a place where the heat can be exchanged into the air efficiently. Typical air-based heatsinks that are mounted onto CPU's are terribly inefficient at drawing heat away into the surrounding air compared to some of the devices (such as radiators) which can exchange the heat contained within the water very efficiently into the air. Due to the efficiency of water-air heat exchangers, typically only slow spinning quiet fans are required to adequately cool the liquid. The end result is a system that can cool the hot components in modern computer systems far more efficiently and quietly than a socket mounted air-based heatsink can ever hope to achieve.
1.3 What are the major components of a water cooled setup
Waterblock - A hollowed block of metal through which the liquid flows. The block is mounted onto the heat source that you wish to cool (eg. CPU, GPU, Northbridge, Disk Drive, etc). Cool water enters the waterblock which transfers heat from the hot object into the water flowing through it. Waterblocks are commonly made out of aluminium or copper as both of these metals are relatively cheap and offer good thermal transfer properties. In fact, copper is the second best thermally conducting metal available (silver is the best). Aluminium tends to be more efficient at transferring any heat stored within it to other mediums (air/water) however, in practise, copper seems to be the more effective metal to use in water-block construction.
Water Heat Exchanger - This is a device that allows any heat stored within the water to be exchanged (transferred) into another medium (typically air - but not always). Common water cooling devices include radiators (similar to a car's radiator but smaller), and evaporative cooling towers (also referred to as "bongs" due to the shape of certain designs). Less common are water cooling devices known as "water chillers", which involve a variety of methods for cooling the water down such as refrigeration, or thermo-electric couples (TEC) sandwich water chillers. These more exotic methods will be covered later.
Pump - The pump is responsible for moving the liquid through the system to allow the heat exchange process to take place. It pushes cool water into the waterblock(s) where the water will absorb any heat, and then is pushed on to the water heat exchanger where that heat can be dispersed into another medium (usually air), before being cycled back through the pump again. Pumps come in two varieties, being "submersible" or "inline". A "submersible" pump sits in a body of water from which the pump inlet draws the water from. An "inline" pump does not require that it is placed in water, instead a piece of tubing may be placed directly onto the pump's inlet, and the pump will draw water through the inlet tubing. Some pumps can work in either configuration, while some pumps may only allow one or the other mode of operation.
Tubing and Hose clamps - The various components of a water cooled setup are connected by tubing through which the liquid flows. The tubing is typically pushed over "barbs" or "fittings" that are the liquid inlet/outlets of each component, and the tubing is then clamped tight around the barb to prevent/reduce the change of water leaks.
1.4 What are the optional components of a water cooled setup?
Reservoir - This is a container that holds a quantity of water. Submersible only pumps will typically sit inside the reservoir to draw their water from, and in this situation a reservoir is unavoidable. In-line pumps don't require a reservoir, but people may still prefer to use one since a reservoir can be used to add ice-cubes in to artificially lower the water temperature when running benchmarks. A reservoir offers an easy place to add more water or water treatment additives (such as corrosion inhibitors) to the system, and they offer a place for any air trapped in the system to escape the water-cooling loop. The drawback of a reservoir is that typically they are not totally sealed and may be prone to spilling or leaking unless they are sitting upright.
Water Additives/Treatment - When mixing different metals (especially aluminium and copper) in a water cooling setup, these exists the possibility of galvanic corrosion whereby the metals will react with each other through ionisation in the water and eat away at their surfaces. This can cause rust (if iron is present), corrosion (for copper) or desposit buildups (for aluminium) which can contaminate the water and/or blocking or slowing water flow which can reduce the efficiency of the water cooling setup, cause damage to the pump, and even cause leaks if the corrosion is bad enough. In order to minimise or completely cancel these effect a water treatment is typically added in systems where mixed reactive metals are present. Some people typically use a water treatment anyway, just to be safe. Other additives can help reduce any fungal growth (which can and does occur in low oxygen environments), or to reduce the effect of surface tension in the water which aids in removing air bubbles from the system (often referred to as "bleeding") .
1.5 Reasons for "Do It Yourself" vs "Kit Systems" vs "Mix & Match"?
Most of the above components can either be made by yourself or obtained very cheaply depending how how resourceful you are. A waterblock can be made from drilling some water channels into a block of metal, a radiator can be obtained in the form of a heater-core from a car at a wrecker's yard, a pump is usually best bought although people have used windscreen washer pumps from cars (also obtained from a wrecker's yard), and tubing can be bought cheaply at a local hardware store. In fact it's quite possible to DIY a whole water-cooling system that works very effectively for under $50 (US). The trade-off is of-course your time (and possible lack of metal working expertise) versus money spent with professionally made products.
Often it is easier to just buy a complete water-cooling system, and to cater for this need there are a range of "kit" watercooling systems on the market that provide all the necessary components from one supplier. Some "kits" are even shipped with their own case (eg. Koolance). Kit systems tend to offer decent performing water cooling solutions suitable for most purposes at a price that's quite competitive with buying components separately. The drawback is that in order to cut costs on the kit systems, certain trade-offs are often made, each of which may have some impact on the final cooling performance of the complete system. A good kit-system will however offer very good performance for your dollar and about the only way to out-perform a well setup kit system is to go for a "mix & match" approach for your components.
If a kit system and DIY is not your style, or you're after something with a little more versatility and cooling power than a kit system, and you're familiar with water-cooling basics, you can opt to "mix and match" components from different makers to produce a water-cooling system that will out-perform any kit system that you can buy. It may not be superior by much, but you can have the satisfaction that you chose components that suited your own needs, and also have the ability to upgrade separate components later. The biggest issue with mix and match is first deciding on what tubing sizes you wish to use and making sure each component you buy matches the other component's fittings sizes so the same sized tubing may be used throughout the system. This prevents the need to use hose size adaptors which can have a negative effect on flow-rates, and thus cooling performance.
SECTION TWO : DETAILS AND EXAMPLES FOR SPECIFIC COMPONENTS
2.1 Water Blocks
The water block is the device that removes the heat away from the hot components in your system and transfers that heat into the water flowing through it. There are many different designs of water blocks on the market, each aiming for the "performance crown".
Water-blocks operate more efficiently when there is more water flowing through them (just like how an air-based heatsink is more efficient with greater air-flow), so an important consideration when buying a block can be the fitting sizes on the blocks, and keeping an eye for the larger fittings sizes which will facilitate a higher water flow-rate.
Some common waterblocks that are on the market today are:
2.1.1 Danger Den Maze 1
2.1.2 Danger Den Maze 2
2.1.3 Danger Den Maze 3
2.1.4 Overclocker's Hideout Z4
2.1.5 Gemini Spiral
2.1.6 Swiftech MCW-xxx Series
2.1.7 Silverprop Cyclone 2
2.1.8 Silverprop Cyclone 5
2.1.9 Danger Den GPU Waterblock
2.1.10 Overclocker's Hideout G3 and G4 GPU waterblocks
This is by no means a complete list by any stretch of the imagination but respresents some of the more popular and better performing blocks on the market. There any many "boutique" makers of blocks that do limited production runs, and even a few very advanced individuals making some very exciting designs, but these designs are often not produced in large enough numbers to be anything more than peculiarities, despite how well some of them perform.
The water-block is responsible for transferring any heat into the water, while the radiator is responsible for removing the heat from the water. Radiators come in a few different basic manufacturing styles/designs, some more efficient than others, but trade off cost for performance.
2.2.1 Tube style radiators
A tube style radiator consists of a single long tube of metal that is curved back on itself a number times. A series of thin fins (usually aluminium or copper) is soldered onto the straight sections of the tube. Such a radiator style can be commonly seen at the rear of wall mounted air-conditioners. Some commercial radiators that use this design method are:
Danger Den Cube
Silverprop SilverStorm Series
Such tube style radiator designs often suffer from poor flow-rate efficiency unless they are well designed, meaning that a pump will struggle to push water through the many curves of tubing and long straights, causing a significant drop in flow rates in the total system. Such radiators also tend to be bulky, and do not cool as efficiently as fin-style radiators for their comparative size. They are, however, cheaper to manufacture and are best suited for scenarios where space is not at a premium.
2.2.2 Fin style radiators (Heatercores)
A fin-style radiator consists of an entry "tank". The water fills this tank and flows through a number of thin flat tubes down one half of the radiator to a collection tank where the water is mixed and flows back to the other half of the radiator through another series of thin flat tubes to the exit "tank" chamber where the water exits. Between each adjacent pair of flat tubes is a concertinaed (folded) very thin metal (usually copper or aluminium) fin that is soldered to the tube at each fold-point.
This style of radiator is often referred to as a heater-core. They get this name as this design is often used as the cabin heating element in many cars. A pump circulates water through the car engine block and passes that hot water onto the heater-core radiator where a fan blows through it and into the car cabin, thus delivering warm air and acting as a heater. Car heater-cores need to be both small and efficient at their job, and therefore their design often respresents one of the most efficient water-air heat exchangers available for their size.
Some examples of commercial radiators that use this design are:
HWLabs Black Ice Series
Overclocker's Hideout 6inx6inx2in Heavy Duty Radiator
A typical car "heater-core"
Such a radiator design is very efficient at heat transfer but is more expensive to manufacture than the tube style radiators. Because of the large number of fins that carry the water from chamber to chamber, and due to the fact that water doesn't have to travel great distances, these radiators tend to be fairly free-flowing and don't impede on water flow rates as much as their tube style radiator counterparts. They are well suited to applications where space is at a premium.
When evaluating the potential performance of heater-core style radiators it's important to not look at just the size and thickness, but also the folded fin density. The tighter the folds (typically measured in terms of "folds per inch" or fpi) the more efficient the heat transfer process is. For example, the HWLabs Black Ice Xtreme pictured measures 12cmx12cmx3cm thick, but has 16fpi. The Overclocker's Hideout (OCHO) heatercore measures 15cmx15xcmx5cm, but has a fpi of 12. For this reason, the smaller Black Ice Xtreme can perform almost as well as the OCHO 6x6x2, despite being physically smaller in all dimensions. The car heater-core pictured is from a 87'-96' Toyota Camry and the fin area measures 22cm x 14.5cm x 3.2cm but has a very high fpi of 24. This helps it to be an excellent performer, being nearly three times as effective as the Black Ice Xtreme despite being not much larger (and considerably thinner) than the OCHO 6x6x2. The car heater-core pictured can also be purchased brand new for much less than the two commercial radiators shown (almost half the price).
2.2.3 Fan considerations for radiators
A radiator by it's nature creates what's known as "static back-pressure" against a fan trying to push/pull air through it. The air has to squeeze past all the fins and this means that a fan which seemed to be moving a fair amount of air when held in the open air, can struggle to make much air move at all when attached to a radiator. For this reason when selecting fans to go on your radiator, it can be important to looking at the pressure/flow-rate curve (also known as the PQ curve) for the fan you're considering.
2.3 Evaporative Water Coolers ("Bongs")
An evaporative cooling tower (or "bong") is a cheap and effective alternative to radiators, often surpassing radiators for cooling performance, but have their drawbacks. An evaporative cooling tower works on the principle of allowing the water to fall through the air, usually by way of a showerhead, down to a reservoir below. The falling warm water will evaporate and cool down as it does so, often to below room temperature. The lowest temperature that the water can get to is what is known as the "dew point", which is the temperature below which condensation will occur. The "dew point" temperature is dependent upon the relative humidity of the air, and can be anywhere from 0C (for 100% relative humidity) to 20+C (very low humidity) below room temperature (see this chart for more information about the dew point of air and relative humidity). It's not hard to see why people are attracted to evaporative cooling when such substantial temperature drops can be achieved.
The best way to feel the effect of evaporative cooling is by standing in your shower at home. Right near the showerhead where the water comes out the water will be quite warm. Now feel the water droplets right near the floor of the shower. They are substantially cooler.
In order to accelerate the evaporative process fans are usually added to blow air upwards through the falling water, and this can dramatically increase the cooling effect.
A quick guide on how to construct your own evaporative cooling tower (bong) can be found here.
The drawback to all this cooling by evaporation is that water can be consumed at a fairly rapid rate, the rate of which depends on the relative humidity and air-flow. In a very dry environment 4 or more litres per day can evaporate in a typical computer sized cooling tower of around 100cm in height, but typically around half a litre of water per day is reported. This means constant topping up to the reservoir is required, or otherwise the cooling system will run dry. All that water evaporating does go into the surrounding air and that can also mean substantially raising the humidity levels in the room in which the cooler is setup. This can make the room feel warm and uncomfortable. Some people get around this by sticking a vent out a window for the moist air to escape outside.
A further drawback to an evaporative cooling tower is lack of portability. A large plastic tower with water sloshing about inside it doesn't make for something that you can easily lug along to LAN's. It's for this reason alone that many people choose to stick with radiator cooling above all else.
A feature of evaporative cooling towers is the sound of falling/trickling water. Some people find a falling water sound soothing, while others find it irritating, and it definately adds to the ambient noise level in the room. In order to address this problem some people use some foam, a sponge, or some nylon (fly-wire) meshing either floating on or suspended just above the reservoir water level to absorb the impact of the falling droplets and dampen the sound they make.
People also complain about the visual appearance of an evaporative cooling tower. Some inventive people have fashioned towers into attractive Japanese-style water-fall features in order to make their cooling towers more pleasing to the eye.
An often overlooked aspect of evaporative towers is the size (power) of water pump required. Many small hobby style pumps that will work suitably in a radiator environment will struggle to push water up much past 1 or 2 meters of height and still maintain a satisfactory flow rate that is needed for the water blocks to operate efficiently. While money can be saved on using a cheap evaporative tower over the more expensive radiators, more money must often be spent on a larger pump.
2.3.1 EbonyKS's HOWTO and experiences for Evaporative Cooling Towers
If you decide that the performance of a evaporate watercooling system outweighs the inconvience of it, there's one thing that i must emphasize:
Bongs are not cheap. I had origionally planed to spend about 60 dollars on mine, however design changes, leaking problems, etc. end up really adding up. My evaporate water cooling giant is almost finished, and has costed me over 150$
With that out of the way, let's have a guide on how to make it.
First, let's talk about the supplies you'll need:
This is undoubly the most important tool of any evaporate cooler. In my cooling system alone, i've probably used more than 10 tubes of this stuff. It's really great. It takes awhile to dry, but seals leaks perfectly, and has been used in all of my connections. I reccomend starting out by getting atleast 5 tubes of this stuff
You're going to have to build the evaporate cooling tower out of something, and PVC is most often used. You're going to need 2 pieces of straight PVC piping, one about 6 inches, for the bottom, and another that's anywhere from 1 foot to 6 feet depending on the temps that you want. You're also going to need a T piece of some sort to attach a fan to. It's reccomended that you also get a 90 degree elbow to put at the top pointing away from your computer if it any water drops escape. For size, i reccomend using 4 inch to 6 inch piping, the later being harder to find. My experences suggest that anything over 4 inch cannot be found at most hardware stores, However, if you do manage to find it, i suggest using it.
The next piece of equiptment that you need is a showerhead. The showerhead, placed at near the highest point in the evaporate cooling system, gives the water a large surface area so it can be cooled better. The picture above is not the type of showerhead that you would use in a bong. Masaging showerheads don't work well, and are mainly designed to pressurize water, which is exactly what you don't want to do. An ideal design has many small holes and some sort of device designed to spread it out evenly. "Open" showerhead designs tend to be poor choices for evaporative cooling
While not a requirement, placing a fan of some sort (panaflo reccomended) will help the performance of your evaporate watercooling system, when attached to the T piece, that connects the two pieces of PVC piping.
Depending on the size of your evaporative cooling system, you'll need an extra pump (any taller than feet or so)
Ehiems make a poor choice as a dedicated evaporate cooler pump (in a evaporate cooling system, you generally need more than one pump, one for the cooling system itself, one for cooling off your computer). I personally use a Little giant NK-2, which is able to pump slightly less than 200 gallons per hour up 7 feet, based on the curve graphs provided by little giant. When looking for a pump for a bong, I highly reccomend checking out http://www.pumpworld.net/ (US only). They are nearly the pump equilivant of headphones.com, and have some of the lowest prices on the net.
If you decide to use the same pump that I have (the Little Giant NK-2), keep in mind that this pump is submersible only, and that you can't run it inline.
Depending on your reservoir, internal or external, you may need some of these barbs. (external would need these)
Now to discuss the reservoir designs, and their pro's and cons.
No reservoir performs the best, however it has one major problem: Frequent refilling. Depening on the size of your evaporate cooler, and the humitiy of the air, you may need to refill your evaporate cooler as often as every couple of hours. While this is ideal for benchmarking, it is impracticle for nearly every other situation.
A internal reservoir, a design where the evaporate cooler (the "bong" part) and the reservoir are all in one piece is the most common design simply because it is easier. It's performance is less constant than an external resovoar, as the water is being mixed from the hot water from the computer, and the cooled water from the cooler (hot and cold being less than 1 degree celc in difference). For this design to work well, a good flow pattern must be established
An external reservoir (what i use) has two typical designs. One of them is based on the no resovoir system, and has a air-tight exteral resovoir filling up the bottom chamber of the evaporate cooler to a certain level. This design works well, but keeping the reservoir air-tight can be difficult, unless resorting to the soda-bottle filling methoid http://www.overclockers.com/tips667/ The term bong in that article describes the shape of the typical evaporate watercooling system, which cathar doesn't like and asked me to not use in this guide) However, this looks kind-of ghetto, and if it not completely air-tight, a leak could over-fill your bong, causing water to spill all over the floor, and destroying your fan.
The other external reservoir design, which i am currently using, is a loop design. This design has the water from the bottom section of the evaporate cooler, into the computer, and then into the reservoir system, where it goes through the evaporate cooling system, back into the loop again. The big benefit of this system is that your water tempatures, assuming that your bong is decently designed, is that your water tempatures will always be below ambient tempatures.
One possible flaw with this system, that i am currently unable to test due to a domestic situation involving the possesion of my bong is the issue of balance between the reservoir and the evaporate cooling system. I would think that connecting the two together with a piece of tubing would balance the two out, however, as of now, i am unable to test this design out.
One major problem that many evaporate coolers have faced is how do you keep the cooler up? There are two major methoids. The first one is building a base for it out of some sort of materal (I used wood on mine, however, i can see this causing some future problems) Then attaching it with some plumbers goop. I use this design.
The other way is to drill a hook into it at the top, and attach it with a elastic rope of some sort to a hook in a wall, however this design works best with the internal reservoir design, then taping it to the side of the internal reservoir.
I personally perfer the base system.
Any questions, comments, or typo's, send EbonyKS a PM.
The pump is an essential element to any water-cooling setup. It is responsible for moving the water through the system and pushing it through all the tight spaces and tubing, and in the case of evaporative cooling towers, up against gravity so that the liquid may fall down and cool.
2.4.1 Impeller style pumps
2.4.2 Magnetic drive style pumps
2.4.3 Gear, Piston and Diaphragm style pumps
The tubing carries the water from component to component. Tubing can come in a variety of materials and sizes. It is of course best to choose the size of the tubing to match your components fittings.
When considering the size of the tubing and matching it to your components, it's important to understand some of the terminology of fitting and tubing sizes. There are two measurements, being the "Inner Diameter" (or ID) and the "Outer Diameter" (or OD). The ID of a piece of tubing is pretty much all that you should be concerned with. The OD of tubing is near meaningless for our needs since it just defines how thick the walls of the tubing is when you know what the ID is.
For fittings, it's important to not confuse ID and OD. You want the "Outer Diameter" of your fittings/barbs to match the "Inner Diameter" of your tubing. It's usually okay if the tubing's ID is up to 1.5mm (or 1/16") too small for the OD of a fitting, as most tubing can typically be stretched at least that much to fit. If you cannot match up a hose with a fitting size (because you may have fittings of differing OD sizes), then you will need to use a hose sizing adapter.
The following table lists common hose/fitting sizes, and the amount of cross-sectional surface area that a particular Inner Diamater offers for liquid to flow through:
2.5.1 Clear PVC plastic tubing
This is the most common and possibly the cheapest type of tubing available. It's nearly transparant which makes it ideal for using phospheresent water additives and showing them off when a ultra-violet light is used in a dark room. It is somewhat stiff and this makes it fairly resistant to kinking, which in turn makes it a decent solution for semi-tight bends. It's also fairly light. It's main drawbacks are that it ages poorly. After a few months it will start to discolor and go "milky", rather than clear. After about a year it can start to become hard and brittle, making it prone to cracking and water leaks at fittings if jostled and mishandled. The rate of aging of the tubing is of course dependent upon the environment in which it is run. Clamping at fittings with this hosing is not usually necessary, but still recommended.
In all, it's a cheap and effective tubing solution for beginning water coolers, and is the tubing type most commonly shipped with "kit" systems.
2.5.2 Silicon tubing
Silicon tubing comes in a range of variants, but we'll focus on the two most commonly used to computer water-cooling.
Eheim is a well respected acquarium equipment manufacturer and they offer a green colored part-silicon based plastic tubing which has many nice properties. It is flexible and light. It is however prone to kinking if made to bend corners too tightly. Quite often it will kink after some time in operation despite holding its shape initially when installed. For the tighter bends it is recommended that either elbows joins, or plastic hose shape guides are used. If you don't wish to purchase a hose shape guide, then some cable ties placed around the kink prone areas are also effective. It is very supple and binds well onto barbs and seals effectively onto fittings. It is generally quite safe to not bother about using hose clamps with the Eheim tubing unless the tubing is barely being stretched over a fitting. It is fairly expensive compared to the clear plastic tubing, but ages much better and can be used safely for years on end without fear of it becoming brittle or leak prone.
True silicon tubing is whitish colored and is the near perfect tubing solution for water-cooling. It is designed to be near inert, ages very well, and is often used in the transporting of chemicals and other substances. It stretches very well, is supple and binds well onto fittings and barbs, and fairly flexible and most importantly it holds its shape well even when bent. Its main drawback is its fairly high cost, being up to 10 times (or even more) as expensive as the clear plastic tubing types.
2.5.3 Garden hosing
This can come in the classic green, as well as other colors, including transparant. Basically very similar to the PVC tubing, but designed to withstand the rigors of aging much better. In most countries, garden hosing comes in a 1/2", or 12mm sizing (among other sizes), which makes it ideal for use in a water-cooling setup. It consists of an inner plastic tube, which is wrapped in a nylon braid for kink resistant reinforcement, and then overlaid with an outer clear pastic shell for additional protection. Heavy, stiff (at room temperatures) and bulky, it is however very effective, if somewhat ugly. Good for turning tight bends, and because it holds its (circular) shape well, it is also good tubing to use for high flow rate systems. It's relatively cheap and available from any hardware store and is often overlooked by water-coolers. It does require good clamping pressure at fittings and barbs to prevent the chance of any leaks.
2.5.4 Other hosing types
There are other hosing types such as pneumatic hosing, car radiator hosing, wire wrapped reinforced tubing can all be used. Such hosing types tend to be overkill for computer water cooling setups, however one of them may offer just the "look" that you're after in your custom system.
2.5.5 Hose Sizing Adapters
This is a short tube typically made out of plastic or brass, which allows two hoses of differing sizes to be joined to each end. It has barbs/fittings to match the sizes of the hoses being attached and allows the conversion of one hose size to another.
2.6 Hose clamps
The humble hose clamp is responsible for binding the tubing tight to any barbs or fittings to prevent the chance of leaks occurring. They come in a wide variety of styles and substances, some of which I'll list below:
2.6.1 Metal clamps
Metal clamps come in a variety of designs such as worm-drive rings, spring style, or wire screwed types. The metal can be regular steel, or stainless steel. Stainless steel is useful for under-water applications where corrosion is an issue, but they are usually more expensuive. Here are some examples of the most common designs in use:
Worm-drive ring - a very common design. Very strong and effective. Many industrial strength tubing applications use this style of barbs.
Spring type - These clamps are squeezed apart with a pair of pliers and are released over the area you wish to clamp. A cheap and effective design, but a little fiddly.
Wire screw type - a very effective design that's light-weight. Not as strong as the worm drive rings but far stronger than you're ever likely to need for watercooling your computer. The only drawback is that the narrow wires may cut softer tubing types if tightened too much.
2.6.2 Plastic ratchet clamps
Plastic ratchet clamps are easy to use and remove and are generally quite adequate for a computer water cooling setup. They don't corrode or react with any metals, and are quite cheap.
2.6.3 Cable ties
The humble cable tie (or zip tie) can make an effective and cheap hose clamp. Because of the low pressures involved in most water cooling setups it is not vital that hoses are clamped to industrial levels of pressure, and if you don't wish to purchase some specially made clamps, then a cable tie can usually let you get the job done with a minimum of fuss.
Cable ties are also useful for helping to straighten out kinks in hosing. Just tighten them firmly around the kinked hose area and they will help the hosing to hold its circular shape.
2.7 Water Additives
2.7.1 Redline "Water Wetter"
(N.B. The following is the "official sales pitch" for the product)
"This liquid product can be used to provide rust and corrosion protection in plain water for racing engines, which provides much better heat transfer properties than glycol-based antifreeze. Or it can be added to new or used antifreeze to improve the heat transfer of ethylene and propylene glycol systems. Designed for modern aluminum, cast iron, copper, brass, and bronze systems."
2.7.2 Car Radiator Corrosion Inhibitor / Anti-freeze
A radiator corrosion inhibitor typical contains boron suspended in an ethylene glycol (anti-freeze) mix. People can also use just pure anti-freeze if they so desire, and for those systems which actively chill the liquid coolant to below 0C (32F), anti-freeze is typically added to the water to prevent it from freezing up. Pure anti-freeze has a freeze point of around -35C and some of the more aggressive water chillers don't bother using water at all in the liquid coolant.
2.7.3 Laundry Bleach
Laundry bleach is an excellent (and very cheap) additive for killing off and preventing any fungal growth in the water system. Just a tablespoon of bleach is typically enough per litre (quart) of water to be effective for many months.
2.7.4 Dishwashing Detergent
A few drops of dishwashing detergent can also be useful when water cooling. Water has a fairly high surface tension, and as such, air bubbles can be some what "reluctant" to move on if they're stuck near some join. A few drops of detergent into the water reduces the surface tension of the water so that air bubbles trapped in the system become less "sticky" to wherever they're hanging out. This aids in removing the air ("bleeding") from the system. It's important to remove all air (or as much as you can) as it can cause such problems as reduced flow rates, reduced cooling performance, encourage fungal growth, and wear out the pump faster due "cavitation" around the pump impellers.
SECTION THREE : EXOTIC COOLING METHODS
3.1 Peltiers (TEC's)
3.2 Refrigerative Water Chillers
3.3 Peltier Water Chillers
SECTION FOUR : PERFORMANCE CONSIDERATIONS THAT AFFECT COOLING EFFICIENCY
This section attemps to summarise the basic physics that happen in a water cooling setup, and what factors will affect the overall performance of a water cooling setup. This is an attempt to give some insight for people thinking about water-cooling as to whether the component or kit they are evaluating for use will perform as expected. As a general rule there is no one single right way to do anything, but there are still certain basic concepts that apply which can affect the performance of any water-cooled setup. Much of the information in this section is derived from this excellent article by Bill Adams in which he analyses many of the effects of changing particular aspects in water-cooling systems.
4.1 Liquid (Volumetric) Flow Rates
4.1.1 Liquid flow rate effects on water-block efficiency
4.1.2 Liquid flow rate effects on radiator efficiency
4.2 Air flow rates
The importance of air-flow rates over
4.3 Water-block design
4.3.1 Base plate thickness
4.3.2 Inner surface area
4.3.3 "Roughness" of inner surfaces
4.3.4 Turbulence inducing designs
APPENDIX A : GENERAL FAQ's
A.1 What's the chance of a water-cooling setup leaking?
Very low to zero. Typical hobby style (impeller/mag-drive) water pumps do not create much pressure. 3-10 PSI is typical of such pumps. This is not enough to push even unclamped tubing away from an unbarbed fitting, let alone burst anything. The biggest issue you will face is the possibility of leaks at fitting/barb joins where the hosing is fitting to some component. If high quality silicone tubing is used the chance of leaks is very low even if no hose clamps are used, however it is always recommended that precaution is taken and hose clamps are used, the metal variety if possible. With a fully tightened hose clamp and quality tubing the chance of leaks is effectively zero.
The other opportunity for leaks arises with DIY waterblocks that have not been sealed properly, or galvanic corrosion eating away at the walls of a radiator or reservoir (if a metal reservoir is used). Both of these scenarios are totally preventable if care is taken to seal any joins, and a radiator corrosion inhibitor is used.
A.2 Do I have to worry about condensation when water cooling?
Unless you are actively chilling the coolant (water) to below the dew-point of the surrounding air, condensation is never an issue with straight water-cooling, eg. a radiator or evaporative cooler setup.
Condensation can become an issue when TEC's or refrigerative water chillers are used.
A.3 What happens if the pump fails?
If the pump fails this means that there is no coolant circulating through the system allowing heat exchange to take place. This is actually not as disasterous as it sounds. Almost all modern Intel and AMD systems have thermal shutdown mechanisms in place whereby if the CPU gets too hot, the system will shut the power off. If your motherboard's BIOS supports this, then turn it on and basically you have no need to worry.
If your system does not have thermal shutdown protection then you may still be okay. Water can absorb a LOT of heat before it gets hot. The still water in the waterblock(s) will slowly heat up (for a very hot CPU at a rate of around 1C per 10 seconds - slower for cooler CPU's). The thing is, water does still conduct heat to the water around it, and also, just like air, hot water does rise due to convectional currents. Depending on how much heat your CPU is pushing out, there may be enough water circulating through convectional currents alone to keep the CPU (or other components) from reaching the stage of thermal death. This can be helped somewhat if the radiator (this doesn't apply to convectional cooling towers) is mounted at some point higher than the CPU. The warm water will rise into the radiator where it can be cooled down. There are in fact some systems that work on this principal alone for silent pumpless operation. They run very warm to hot, but as long as the CPU isn't overclocked and over-volted, then safe CPU temperatures can still be achieved.
If you have no thermal protection, and if your radiator (if you have one) is not mounted higher than the CPU, then basically you will run the very real risk of CPU death, although it will take a fair amount of time (around half an hour or more) for this to occur.
A.4 What happens if the fans fail (on a radiator system)?
Surprisingly this is not that big of an issue. While it's true that the radiator does need at least a small amount of air-flow to cool the water flowing through it, this is not strictly necessary. Unless you are dealing with very large heat-loads (such as experienced with TEC's), even a highly clocked and volt-modded CPU won't put out more heat than most radiators can deal with without airflow. Unless the radiator is tiny in size, it will effectively act as a very large passive heatsink.
The water will get very warm to hot however, approaching up to 60C in temperature if the radiator is fairly small, but at this point the radiator will start creating its own convectional air currents due to the level of heat involved and as a result move enough air to keep the water from getting any hotter. This will prevent the CPU or other hot components in the computer from overheating to truly dangerous levels, although they will be hot.
What may be of the biggest concern is the pump in such a circumstance. Many hobby pumps simply aren't designed to deal with water temperatures much in excess of 50C (120F) for prolonged periods of time, however since the water should never get stupidly hot (>70C) most pumps will quite happily survive short bursts of high water temperatures.
A.5 What happens if the water system runs dry?
If the water system runs dry (such as may happen with an evaporative cooling tower or when using an unsealed reservoir) then basically you're in trouble. In this situation you need to rely on the computer system to have some form of thermal shutdown in place. Almost all Intel and most modern AMD systems have a thermal shutdown mechanism which can be enabled in the BIOS. If your motherboard supports this, then turn it on. The water-block on the CPU or other components will prevent that component from getting too hot too fast since they consist of a large chunk of metal which can soak up a large amount of heat before getting really hot. This will give any thermal shutdown mechanism a fair amount of time to activate and protect expensive equipment.
What may be an issue (assuming your computer system has safely shut-down) is the pump. Most pumps require water flowing through them or to be sitting deep enough in water to keep themselves cool. While short periods of running waterless won't do a pump much harm, sustained waterless running may cause damage such as overheating the motor, wearing out the bearings on the impeller (for impeller style pumps), or even melting certain plastic parts on the pump.
In order to get around the issue of turning the pump off when the system automatically shuts down, some people use a 12V relay circuit for turning the pump on. This is basically a small box which has a mains power cord going and out of it and a 12V power connector. The computer's PSU plugs into the relay box and when the computer is turned on, this throws a magnetic relay switch inside the box which turns the mains power on for whatever device is attached to the relay box. In this way, the operation of the pump can be tied to the operation of the computer system.
APPENDIX B : FURTHER INFO AND ONLINE RESOURCES
B.1 Commercial Water Cooling Websites
http://www.dangerden.com/ - A USA based maker of water cooling blocks and reseller of additional water-cooling equipment, as well as customised kits. One of the most well recognised and popular brands on the market. Their latest Maze 3 design combines good looks with good cooling performance.
http://www.overclockershideout.com/ - Also a USA based maker of water cooling blocks and reseller of equipment and customised kits. Well noted for their good looking shiny silver polished blocks with color coded barbs. They also offer kit+case systems.
http://www.swiftnets.com/ - A well-known USA brand of some of the best air-coolers on the market has turned their attention to water-cooling as well. Swiftech water-cooling designs focus on brute-force water-cooling with large copper blocks to soak up the heat and pass it on to the water. They offer a range of blocks to suit your needs and provide complete kits for easy starting. They also offer kit+case systems.
http://www.koolance.com/ - A well-known brand of kit-complete water cooling cases. They sell everything you need for a water-cooling setup inside a case that they have pre-modified for the various components they have put in. Water cooling for beginners doesn't get any easier than this. The performance of their systems is fairly average compared to other kits or a well put together mix & match system, but they offer a cheap and nearly fool-proof entry level into water cooling while providing cooling performance that will exceed what any air-cooler on the market can offer, but without all the noise.
DTek Customs - A US based supplier of the Gemini Spiral and the closely related Spir@l waterblocks. They offer complete kits based around these surprisingly highly performing and small blocks.
http://www.silverprop.com/ - An Australian based water cooling block manufacturer well noted for their innovative designs coupled with brute force water cooling. They tend to take a no-compromise approach on some of their top-end blocks which makes them a little more expensive than others but they perform extremely well because of it. They also resell additional equipment and provide a range of complete kits.
B.2 Water Cooling Related Websites
Overclockers.com Water-cooling Resource Page - Copious amounts of information about water cooling - most of which contributed to this FAQ.
Procooling.com - An excellent independent water cooling review and informational web-site
B.3 Specific Water Cooling Performance Analysis and Informational Links
Quick guide on how to build an evaporative cooling tower (bong cooler)
Radiator Heat Dissipation Testing - An excellent article - highly recommended
B.4 Author of this FAQ
The author of this FAQ is Stew, who most often goes by the Internet forum handle of "Cathar". He is a professional software programmer by trade and a general computing enthusiast who loves to dabble in all things computing related. His interest in water-cooling sparked off in mid-2001, and after much research built his first system in December 2001, which has since gone through numerous revisions in that time. He may not have first hand knowledge of everything presented in the FAQ above, but has tried to keep his "ear to the ground" on most things liquid cooling related, weed out the information from the mis-information, and present what he has learned over the last 12 months.