Skip to main content

The Liquid PC

Article - the do's and don't's about using water to cool your PC

Dark blue icons of video game controllers on a light blue background
Image credit: Eurogamer

I woke up recently and thought "lets run gallons of water into my extremely expensive computer and see what happens". Admittedly it sounds like rather an odd thing to suddenly lust after, but actually, when it comes down to it, it's both quiet and more efficient than regular heatsink and fan cooling setups. Quiet, because it features only the one fan, and more efficient, because… didn't you learn this stuff in school?

The inside of a water-block - you can see where the water shoots in opposite the processor's core

It's all about Energy

Alright, basically, with current heatsink/fan methodology, you are faced with a big heat source, and in order to get the heat out of the system, you conduct it away with a heatsink. To prevent the heatsink itself becoming far too hot and incapable of performing correctly, you use a fan, either blowing air onto the heatsink's fins, or sucking the hot air out and away. Either way, the idea is to displace heated air with regular air. And it works. Using water to cool your PC works in very much the same way. You attach a metal block (known as a water-block) to your CPU in place of the heatsink, and you use water (which can be cooled elsewhere of course) to keep the processor chilled. By constantly pumping water over the surface of the processor, you conduct the heat away. The tricky part is cooling the water when it's not running over your CPU. Most people tend to use a network of pipes with a big fan blowing onto them, whilst others have hooked up elaborate fridge systems, and some even forgo the need for such external devices by employing a Peltier, a device which uses all sorts of ghastly physics to create an area of extreme cold on one side of your heat-block, and an area of extreme heat on the other. This is of course, rather dangerous.

Swiftech's water-block, firmly installed on top of the CPU


At the moment, those of us in England only really have the one choice anyway, to use a water-block with a water-cooler and a pump. Generally speaking, it's not that hard to set up - you just have to make sure all the pipes fit and that you have space for everything to stand freely - but actually getting hold of the stuff is quite troublesome. There are two retailers that actually have stock. One is The Overclocking Store, which features a line of Swiftech setups that work on Socket A Athlons and Durons. Unfortunately, the kit we ordered seemed to be the first they had ever sold, and we had to contact manufacturers Swiftech for instructions on how to perform the install. We used the Swiftech-recommended Eheim 1046 centrifugal pump (which was purchased separately), but even today we are still searching for more of the appropriate piping to make the thing work. The piping provided with the kit was in no way sufficient, and despite several trips to B&Q, we're no closer to getting things working, because of the obscure measurements involved. Of course, this merely compounds the fact that the kit seems to be exceptional in every other sense. Instead of using a clip to keep the water-block on the CPU, the block is actually screwed down onto the motherboard using stand-off screws. The block covers the entire CPU and unlike other kits, the water approaching the CPU is actually pushed directly onto the core area of the chip. It'll cool quite nicely, we fancy.

SENFU's kit, all nicely laid out


The alternative to this highly fiddlesome Swiftech setup is a similar deal from rivals, which seem to be a one-man outfit that resells SENFU products. SENFU offer a similar "all in one" setup, with a slimline water-block, pump and water-cooler. The SENFU pump though is considered to be flimsy and rather unreliable, as was proven when one of the EuroGamer staff bought some SENFU kit and watched it pack in a day later. Thankfully, is a very amiable outfit. Not only did they replace said pump within days free of charge, but they are actually helping us iron out the problems we are having with the Eheim pump and our Swiftech setup, which we consider to be above and beyond the bounds of duty for most retailers. Their kits are actually variable too, with more tubing available on request and lots of extra options for those who need them. Payment is either by direct bank transfer or cheque, with no online option as of yet, but the service is very impressive otherwise. Actually using the SENFU equipment is tres facile, too. The water-block sits quite happily on the CPU, with reinforcement from a clip across the top and water is pumped in and out with no great fanfare. Unlike the Swiftech system however, which is designed without use of an accompanying container of water in mind (effectively closing the cooling system off to the world), the SENFU setup works best with a reservoir (Tupperware is great for this) and that water be pumped in and out of that. The upshot is that you can keep an eye on it more easily for telltale signs of problems (like bubbles), and that you can top it up or even completely change it from time to time without having to disassemble your PC.

A Peltier - don't try this at home, kids!


The benefits of water-cooling your PC are debatable. Many people will of course tell you that "it's cooler!" but when you think about it, room temperature is your obvious target. Any possible achievement likely depends on what you consider to be normal in the first place. The Athlon this article is being written on, for example, idles at around 35° with the case on and no real outside ventilation other than the power supply fan. Under load it can approach 52° or thereabouts, and drops back down soon thereafter. With water-cooling, I can run water that is chilled to room temperature (which Motherboard Monitor informs me is 22°) by a big 120mm fan over the surface of it, and let that conduct heat away. The chip's temperature depends on how quickly the water is pumped and how efficient the fan on the water-cooler is. In my brief experience, the CPU idles at about 25° with water-cooling installed, but this figure goes up to as much as 30° or 35° under load. Changing the fan or the pump may well yield more impressive results, but if you already have a very efficient heatsink and fan installed, you may discover that the improvement is marginal.


Practically then, what are the benefits of water-cooling? If sound levels are important to you, cooling your processor with a water-based setup will keep temperatures in check and produce much less background noise than a heatsink/fan combo of similar performance. Overclocking is also an option when you know that temperature is unlikely to be an issue. In reality though, these are minor points, and water-cooling is probably best left to those with more time than sense, or those who want to err on the risky side of things with their Peltier coolers. Over the next few weeks we hope to review both the Swiftech and SENFU setups, which can be found at The Overclocking Store and respectively.

Read this next