How to Watercooling - Extensive

Date: 27.04.2003


Watercooling, it is something that just about any PC enthusiast envies and admires but few are willing to take the plunge and get it. It is cold, it is quiet, and it looks awesome. To the general population either Watercooling seems too complicated and risky, or so expensive that you would never consider spending that money on anything other than a new video card. Times have changed since the days of “experimental Watercooling” and this guide hopes to help you put together your own Watercooling system in words and explanations that just about anyone can understand. To spark your interest note that water is ~30 times more efficient than air at transferring heat!


I will assume that you know about air cooling, and the principles of general heat transfer associated with running a stable PC. The CPU (and GPU) of a computer generate a lot of heat, these days it is so much heat that without something actively taking that heat away it is very possible that the computer will lock up, or in the case of AMD processors melt into wasted computer goo. You need a heatsink to absorb and dissipate that heat, and the more heat you take away, the cooler and more stable the CPU is. Typically people utilize a heatsink made of aluminum or copper with some sort of fan attached to get the air inside the computers case to carry excess heat away from the CPU or GPU. However, air cooling has its limits and anyone who owns a quality heatsink and a fan so loud that you can’t sleep in the same house as it knows what I am talking about. With air you can only go so cold, or so loud before you have to call it quits. Remember that uncanny ability of water to efficiently transfer heat? Why not apply those principles in the same ways as air cooling? Watercooling has been so successful and appealing that many manufacturers have made it easy to get started with everything from custom radiators to completely assembled Watercooling systems. The common features between water and air cooling end there, to cool with water you need to start playing a whole new game (a game with rules that are quite easy to learn).


You will need some basic elements to put together a water cooling system, one of which is a computer that isn’t “micro ATX” format ;). These following components are pretty much shared in all systems but their appearance and application often times varies greatly.

-Water pump: there are in-line pumps that often also work as “in-reservoir” pumps. Try to find one that does at least 100 gallons per hour (GPH)


In-line Pump


In-Line pump w/ water flow


Submersible Pump

-Waterblock: the “heatsink”, get one that is fit for your processor (AMD or P4 etc.)


CPU Waterblock


GPU Waterblock


Simpler CPU Waterblock


CPU Waterblock cut-away


The internals of another Waterblock

-Radiator: Cools the water, (many types, shapes and sizes)


160mm X 80mm Radiator


Cut away of radiator

- Reservoir: Stores water, (only if you are making a reservoir system)


Standard reservoir


Bay-Res” reservoir w/ UV sensitive liquid

Ingredients Continued

-Tubing: comes usually with an internal diameter of 3/8”, ½” (or sometimes ¾”) Vinyl and Silicone make the best tubing.


- Clamps and Barbs: these prevent leaks and hold tubing in place


90 degree brass barb


Plastic Barb

- Distilled water: Does not conduct electricity or contain added minerals. Make sure to also get something like “Purple Ice” or “Water Wetter” to prevent corrosion. Water wetter cleans the inside of the system, makes heat transfer more efficient and also prevents corrosion (it is designed for race-car radiators!) I do not recommend anti-freeze because to refill you would need to dispose of all your liquid at some sort of car garage to be safe. Many companies sell various types of coolants to add to your water. In addition to this there are cosmetic additives which can change the color of your liquid, or make it “glow” in UV light. These should not replace other additives to prevent corrosion unless specifically noted by the manufacturer.


Water Wetter


UV sensitive dye

- Tools: You will want screwdrivers, something to cut hose and an outlet. Other things you may need or want are sealants, a bucket and potentially some towels ;).

Basic Principles of water cooling


Diagrams of watercooling setups

There are only a few relatively simple components of water cooling, and the rest are just details. The most important component is the CPU or GPU water block. This acts just like a heatsink, cool water flows into the Waterblock and takes away heat and then flows back out into the pump or reservoir. The Waterblock usually has some sort of internal “water maze” that the water flows through in order to maximize heat exchange. The maze pattern, or internal structure varies from manufacturer to manufacturer. The best Waterblocks are made of silver but they are ultra rare, copper and aluminum Waterblocks are more common and they seem to get the job done (copper slightly better than aluminum since it is better at transferring heat.)

Warm water flowing out of the Waterblock makes its way to either a water reservoir or an inline pump. The pump pushes this water to the radiator. The radiator is composed of many thin metal fins much like a typical heatsink. Through these fins travels a winding tube made of some metal, the water flows through this tube and gives its heat to the fins. The fins are usually then cooled by air being pushed or pulled (pulling is more efficient) through the radiator by some sort of fan. From the radiator the freshly cooled water flows back to the Waterblock. The entire process is actually rather simple; it is the details that make water cooling appear complicated.


There are two main schools of thought when it comes to water cooling. The reservoir system and the inline pump system. I will start with the inline pump system. In the “inline” system there is no water reservoir, all of the water used in the unit is contained within either the tubing (usually ½” internal diameter), the Waterblock, the radiator, or the pump. The water is constantly being circulated throughout these components. One benefit of this is the space; without a bulky water reservoir all you have to fit in your case is the radiator, Waterblock, tubing and pump. Pumps are typically smaller than reservoirs (which are often designed to actually contain pumps). There are two main drawbacks to this method. One con is the noise, submersible pumps are typically quieter. Although being “inline” doesn’t necessarily mean that the system will be loud (it depends on the quality of the pump used).

Another drawback is the “bleeding procedure”. In order to have a self contained water cooling system without a reservoir you have to have the ENTIRE system “air free”. Everything must be air tight in order to prevent air from getting in. This is where the bleeding procedure and the bleeding line come into play. To fill the system you need to initially fill it under water for some time, in order to ensure that all of the air bubbles are completely ejected from the tubes and other components. The bleed tube is an extra length of tube at the highest point in the system designed to collect the gasses that will eventually dissociate from the liquid. It also acts as a small extra source of coolant in the case of evaporation (which if you did a good job you hopefully won’t have!) To use one you simply have to use a “T” or “Y” tube connector and attach a length of tube that just contains extra coolant with a plug on the end. This length of tube ,as you will see later, should be located between the pump and the reservoir. The point of this entire procedure is to eliminate traveling bubbles, think of them as blood clots. If they collect in your Waterblock (brain) then your CPU will potentially overheat, or in the case of your brain, die.

Reservoir systems approach Watercooling differently. First of all, there really isn’t much of a bleeding procedure. In fact if you want to you don’t have to do any bleeding at all. You simply immerse the pump within the reservoir and fill it up with coolant. Before closing off the reservoir it is recommended that you run the system for a while, adding water until the block is completely full and you cap it off (this procedure will be discussed in detail later in the guide). This way air bubbles will really be eliminated or minimized. The last thing you want is a pocket of air traveling through your tubes, if this were to happen it would most likely just displace in the reservoir, unlike inline systems where that pocket of air could potentially be circulated over and over again.


Notice the pump submerged and contained within the reservoir unit

You must match components, in several dimensions. The first step is to find tubing that matches the hookups (or barbs) as far as internal diameter goes. You will want to match a Waterblock with ½” barbs to tubing, a radiator and a pump/ reservoir that all share this same ½” diameter standard. If you were to attach different sized tubing or another component somehow it would not benefit the entire system; a chain is only as strong as its weakest link. If a component is of a smaller diameter chances are your overall flow rate will decline as a result of that bottleneck.

Another factor to be aware of is corrosion. If you have a copper radiator and an aluminum Waterblock chances are that the electromagnet value of the copper will steal electrons from your aluminum Waterblock through the water. You don’t need to know the details of it, just know that there will be deposits and corrosion throughout the system as a result of the imbalance. However; there are ways around this. There are chemicals that you can add to the water that prevent this from happening. You should add some sort of special PC water cooling coolant additive, water wetter, purple ice or some combination that you see fit. Keep in mind this applies to your y-splitters and barbs, if they are brass they contain copper and WILL corrode with time!

People who are into Watercooling have varying opinions about what to use to actually cool the water. Some people believe in using old radiators from cars, some people believe in using thick, clunky heater cores and others just use special radiators designed to work well for Watercooling systems. I will focus on radiators in this guide for one simple reason. Heater cores and car parts are often times big, clunky ugly things to have sitting in or around a PC. In these days of “computer fashion” I believe it is social suicide to plop some big ugly component right along side your cathodes and LED fans. Although some contend they may cool slightly “worse” than these other options often times you can find nice looking radiators that will fit right on an 80mm fan port, or other standard computer sizes like 120mm or 80x2mm fan ports. Since you will most likely want to show off your new Watercooling kit to pick up some fine ladies you don’t want them gawking at your 86 Corvette radiator stuffed in place using rubber bands and zip-ties!

Powering the Watercooling pump can accomplished in 1 of 2 ways. Either it will have its own plug that you can run out of the back of your case, or you will have to Molex it (or wire it directly into your power supply). What method you use is up to you since they both have their benefits, that mostly being convenience. Remember: ground your setup in some sort of surge protector, de-ionized water is not supposed to conduct electricity but at that wattage there could be some measure of electric transfer between block and CPU/GPU (this would not be good).


This reservoir houses it’s own pump. Note that the plug would be difficult to squeeze out the back of a case. Some pumps come with plugs that you install once the wire has cleared the rear of your case.


Notice how the power cord exits the rear of the case through a slot

The method of fastening the Waterblock varies, and I recommend only ONE method. The method I endorse is one that is either designed to specifically fit onto the socket like a normal air heatsink, or one that screws into the motherboard via the 4 screw holes surrounding most modern CPU sockets (many utilize a plexi glass plate and cushion springs for the screws). Other methods involving brackets and other “sandwiching” devices all too often are fastened unevenly, break, or apply uneven pressure. For these reasons I recommend you get a pre-made reliable water block that fastens in a tried and true method. If you decide to use a sloppy bracket method or something similar do not be surprised if you crack your core, or worse discover that it has fallen off and your system is fried. Lastly, use a CPU shim on AMD systems and some form of “arctic silver thermal compound”. Using a cheap thermal pad or toothpaste will just do to negate the effects you are trying to achieve by using Watercooling in the first place.

You will need to avoid the growth of microorganisms. If you are using simply de-ionized water you aren’t protecting yourself from microorganisms. You might be laughing now but look at this image taken from the Hard forums (this image posted by user “Dyrewolfe”). While looking for information on coolants I came across this gem. The lesson; unless you want nasty stuff like this in your PC add some coolant or a product like Water Wetter (Incidentally Dyrewolfe noted that this was the result of “well water”).


What details you deem valuable depend on your personal preference, financial situation and space to work with. All of the methods work well and you won’t be disappointed at the upgrade if you work carefully. If you have a little amount of space yet you want a reservoir system there are products like the “Bay-Res” that fit a full sized reservoir within a 5.25” bay, likewise if you are tight on space there are radiators specifically designed to be fit over normal fan bays, so you sacrifice very little in way of internal case room. Whatever system you use be careful in putting it together, and remember to test it before you actually fit it inside your PC.

Deciding What To Buy

Decide on a tubing size, I recommend ½”, you may get better water flow and to be honest the big thick tubes just look cool! Remember to match all of the components with this size. You can use silicone or clear vinyl tubing which are usually both available readily at your local hardware store.

I think a good idea to start with next when putting together a water cooling system is the radiator. You want to find a radiator that will fit your application. I use a radiator that is 160mm x 80mm, it fits directly over a dual 80mm air intake. If you don’t have space like this you should find a place where you can find a ~80mmx80mm radiator. This would preferably be on an intake, so you are cooling with fresh air. If you mount the radiator on the exhaust you will use warmer air, although you won’t add slightly heated air to your internal case temps. The choice lies between a cooler CPU or slightly warmer internal ambient air temperatures, if you ask me the choice is clear!


Notice the radiator will be receiving exhaust type air.


My radiator fits directly behind this dual 80mm fan intake

Now that you have a radiator picked out, and a spot for it you will need to decide between an inline system and a reservoir solution. Find where you will locate your reservoir, and find an appropriate pump. I recommend that the pump be at least 100GPH, and remember to match up the tubing diameter! If the pump is submersible then simply make sure it fits inside your reservoir, and that the reservoir has the proper openings for the pump and all of the necessary tubing. If you use something like a bay reservoir then make sure you have a small enough pump to fit inside, or room elsewhere in your case to house the pump. The two most recommended pump brands are Eheim and Danner. Both of these come in many models etc, but you shouldn’t buy one with more than 300GPH pumping capacity, since given the nature of the system the bottleneck of the water flow is likely not the pump itself.

Find fasteners and clamps for every junction made between tubing and component. You will want to close off every single one to prevent leakage. The two basic types of clamps are pictured below.



Note: there are other types of clamps to be found, these I find are the most common and easy to use.

Whatever water block you want is likely to fit on your motherboard. Some motherboards do not contain screw holes, and others are blocked off by capacitors etc. You will want to check your motherboard for compatibility. You will want to find a block that is made of the same material as your radiator and fittings (if made of metal). Copper blocks seem to perform the best, but I use an aluminum block coated in silver and it also performs fairly well. Whatever you do get make sure it has the following three things: a good method of connecting the block to the motherboard, the internal metal matches that of your other parts, the fittings match the diameter of your other parts. For the performance of individual Waterblocks you will probably need to hit the forums or individual product reviews. Keep in mind you will see some very basic waterblocks, and you will see much more complicated expensive blocks: rely on ratings not simply appearances! Another feature to look for is a smooth surface on the block for the CPU to make contact with, if it is anything less than a mirror shine you want to look into one with a cleaner surface.


This Waterblock fastens on using the usual “push and clip” method common for AMD processors.

There are other ways of mounting radiators and reservoirs. You can mount some radiators and reservoirs externally, in fact you might go so far as to store your reservoir in a fridge. As I said before, I am biased towards clean, nice looking, practical and reliable systems so I don’t usually go for such a huge mess of tubes and wires. This system is completely externally mounted and manufactured by a company called “Koolance”.



If you choose to buy a complete kit, this section of the quest will become rather self explanatory. The kit will likely contain directions, or the manufacturer will provide them online. My first system was a complete kit and it took next to no time to put together, test and get installed. And it completely blew my air cooling set up (Alpha PAL8045 W/ Delta 38 screamer) out of the water. If you do not have a complete kit, or your manufacturer provided poor directions then the following should help guide you in the necessary steps and precautions. Just remember; be careful, and test, test, test!

Since you have an idea of where you want your individual components to go you will want to cut your tube to fit the application. Remember; cut the tubing a little long so you don’t come up short. Cut the ends at 90 degree angles, and when fastening make sure they fit on nice and clean (fastening can be a struggle at times but it is a necessary evil). The following section will describe basically where your tubing optimally should go.

Bleeding and Filling

Do not install any of the components into the system yet; simply figure out how you will attach them, given that the system will be preassembled when you do finally mount it in the case. Start with the length of tube going from the output of the pump to the top of the reservoir. The bleed line is optional, but it should be between the radiator and the pump connected by a T-splitter. Once that is solidly in place take the output from the bleed and run it into the radiator. You will want to put the clamps on the tube before you fit them onto the barbs. Clamp both of these tubes down. From the output of the reservoir run tubing to the Waterblock, there is a specific way to attach this tubing. Make the cool water input either to the center barb on the block or to the lowest barb if the block is horizontal (in that order of importance, if there is a center barb choose that for the input over the lower barb!) Clamp both of those down. Next attach the output of the Waterblock to the tubing that will input on the reservoir or pump. DO NOT CLAMP THIS DOWN YET! This way you ensure that the freshly chilled water from the radiator goes straight to the CPU. By attaching the hoses this way I found results several degrees Celsius lower than I did with the radiator before the reservoir. I also had better results with the radiator attached to an intake air source versus an exhaust port.


A close-up of the pump output connecting to the top of the reservoir


The input and output tubes from the radiator.

*Note: If you are installing a GPU or chipset cooler in addition to the CPU simply split the cool radiator output into enough lines to transfer cool water to your GPU or chipset cooler. Run the exhaust from this into the input of the pump or reservoir by means of reverse Y or W-splitters.

If this is the first time running your system you will want to flush out all of the components. Submerge the reservoir and the pump into a vessel containing water (de-ionized or tap will work here). Now make sure that the input to the reservoir is pointed into a sink to drain the “dirty water”. Suck on the bleed tube until it fills with water and cap it. Turn the pump on and you should see that the system completely fills up with water and pumps it out through what will be going into the reservoir or pump input. Run it until the water is clear, and then run it a little while longer. Turn off the pump and drain the system of the tap water.

Now repeat these steps in some vessel containing your distilled water. I recommend you measure out the amount of water so you can approximate how much coolant to add to the mix. Make sure the pump input is draining into the vessel this time so you keep all of the liquid in place. Once you have shaken all of those pesky air bubbles out and the water is flowing evenly you can think about adding your coolant to the mix (this will be after about ~15 minutes or so of component shaking and turning of the pump off and on). Mix in the coolant so that it flows in the desired concentration. Now making sure that no air gets in connect the input of the pump/ reservoir under water. Make sure everything is still copasetic and there are no air bubbles. If this is the case then you are set for testing! You should dry off everything and run the closed system for at least a few hours to test for leaks. If everything is fine then you can install it in your case. Attach everything as you previously planned (making sure to keep the bleed line elevated if you have one) and then run the system with the computer off. Test this for a few hours or overnight and see if there are any leaks, dead pumps or kinks. When installing the components make sure not to rest tubing on hot objects, or twist and bend them in such a way that they kink. A kink would seriously impede your water flow and effect cooling and is more common in 3/8” tubing.


If everything appears to be working correctly do another check.

Do you have thermal compound on the Waterblock, is it fastened correctly?

Are there any kinks or leaks?

Is everything hooked up as you like?

If so it is time to power up. Immediately check your bios for your CPU temp. If the temperature readout seems reasonable then go ahead and boot into windows. Using Motherboard Monitor check your temps, do they seem correct? If so it is time to really test the Watercooling. I recommend Prime 95 to max out the CPU and get results that really push the Watercooling to its limits. Once you are satisfied that everything is working well feel free to experiment in overclocking or whatever else you see fit!

Final Words

You are probably wondering what sort of results to expect. If your system is really maximally efficient you should expect idle CPU temperatures to reflect the ambient air temperature in your room. I have seen steady idles as low as 13 degrees Celsius in my set up, and this is probably due to some of the cold air my intake sucks from the winter outside. However, these temps don’t stay that low and will rise with CPU activity. Expect your max temps to drop significantly, as mine are typically lower than 45 degrees Celsius even when overclocked. Expect an average CPU temperature that reflects an average ambient room temperature (or slightly warmer if your radiator is hooked up to exhaust air). If your radiator is hooked up to an exhaust then you should expect your CPU temperatures to reflect that of your internal case environment. This can be drastically warmer and is the reason why I recommend cool air intake for the radiator. If your results are not like this then chances are you are doing something wrong. In my experience if you take your time and do things right you can expect very good results like this from a system with 3/8” tubing, a reservoir and aluminum block. Make sure you are monitoring from on socket sources, and not diodes. Diodes typically are not as accurate as on socket sources, and will typically display a temperature that is cooler than the actual core by a few degrees. While it may not matter for the average user, it can become rather important if you are overclocking! On a similar note, be aware of mechanical failure. Just as a CPU fan can die, a pump could potentially die. Use precautions against disaster. By using a program like CPU idle you can not only lower your overall temps but you can make sure that if your CPU reaches a certain temperature it will shut down the computer. Be safe, have fun and don’t go frying too many CPUs.

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Copyright © 2002 Øyvind Haugland
Sist endret:  13 januar 2019

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