James Hunt lays out the fundementals of this effective form of PC cooling
For many PC enthusiasts, watercooling is still something of an unexplored frontier. You might be used to playing with extra fans, drilling additional ventilation and positioning hardware to reduce air pockets, but until you’ve made the switch from air to liquid, you’re always running a second-best system. The days of the humble fan are numbered.
Keeping your system as cool as possible isn’t just a way to keep your hardware within overclocking tolerances; it also extends the life of components and reduces the amount of noise you have to deal with. For all its simplicity, cooling components with air is inefficient. Fans can get clogged with dust, and air itself isn’t that good at conducting heat. Watercooling, by comparison, is so good that it does the work of several fans in a fraction of the space. So why wouldn’t you want to give it a go?
If you find watercooling hard to get into, this guide should help you tell your loops from your radiators, show you the difference between the good brands and the bad ones, and give you all the information you need to know in order to start tinkering with watercooling whether you’re interested in making your PC quieter, faster or just more efficient.
How Does it Work?
Fans cool your components by allowing heat to dissipate into the air and then blowing the warm air away so it can be constantly replaced by new, cooler air. This, as we just mentioned, is an inefficient process. Air accepts heat quite fast, but not as fast as many other materials. This is why heatsinks exist: because metal transfers heat away from the component faster than air can and can dissipate it into a larger volume of air.
In comparison to air, water has both a higher thermal conductivity (so heat is transferred faster) and a higher specific heat capacity, meaning that if you have the same volume of water and air, the water can hold more heat before it starts to feel hot.
Watercooling systems use liquid tubes to run fluid across components, which absorb the heat within them. The water then passes through a radiator, which acts like a heatsink, transferring heat out of the water and cooling it back down again, a lot like a car radiator.
You can make bespoke watercooling systems or buy them off the shelf, but regardless of which route you take, you’ll always find that they’re made up of the same components: a pump to move the coolant, a tube (‘loop’) to contain the coolant, the coolant itself and a radiator that can dissipate the heat. Radiators may be heatsinks, but it’s more common for them to contain a fan.
Although some cooling systems require you to attach the pipes directly to the component with thermal compound, it’s also common to find water blocks that are heat-conductive pieces of metal, which contain hollow tubes where water can flow. While heatsinks dissipate water into the air surrounding them, water blocks dissipate the water into the water that flows through them.
Watercooling units can be applied to any heat-generating component, but they’re most commonly applied to CPUs or GPUs. You may want to watercool any number of other components, from motherboard northbridges to hard drives and SSDs. Anything that generates heat will benefit from being kept cool. The only question is what sort of expense you’re willing to go to in order to make that happen.
It’s worth pointing out that watercooling is mostly useful for hightemperature systems where components are being continually stressed, whether that’s because you’ve overclocked them or because you run them at high-capacity for a long time (gaming and video encoding are two tasks where watercooling would definitely benefit the hardware). If you run a low-temperature system, air cooling is probably more than enough to keep the temperature at safe levels – though watercooling can still provide a quieter method of removing heat from components.
Obviously, watercooling carries some small risk. The development of bespoke closed-loop watercoolers means it’s highly unlikely that you’ll have any spillage accidents, but it’s not completely impossible. Similarly, it’s wise to test bespoke loops extensively before you run them in an actual system, just in case there’s a puncture or loose connection somewhere in the system. The risk is low, but it’s worth remembering that a problem with your watercooling can be considerably more disastrous than a failure with air cooling would be, so don’t get complacent, and don’t put any hardware at risk unless you can, on some level, afford to replace it.
The Hardware
We touched on this briefly, but watercooling systems come in two forms: homebrew or bespoke self-builds, where the entire loop is constructed out of individually purchased components, or off-the-shelf prebuilds, where you buy the entire system and simply install it as you would any other cooler.
Prebuilds are sometimes referred to as ‘closed loop’ systems, because they don’t require the user to manually add coolant. It starts with the amount it needs, and because the loop is closed, it shouldn’t ever need replenishing.
Buying a prebuild has its advantages, especially for beginners. It’s safer, because it’s been professionally constructed. It’s simpler, because you don’t have to check compatibility between multiple components or learn about coolant levels yourself. And it’s easier to get hold of, because even high-street computer shops sell watercoolers.
But bespoke systems have their advantages too. You can tailor them to your personal needs, and they’re cheaper to construct. It’s also easier to apply watercooling to non-standard components. Off-the-shelf systems are largely aimed at CPU cooling, with the possibility of GPU compatibility. Bespoke watercooling can essentially go anywhere you like.
We’ll cover individual closed-loop models later in this piece, but if you want to build a bespoke system, here’s what you need to look for:
A Waterblock: Make sure you buy one that is compatible with the hardware you want to cool. CPU waterblocks tend to be universal, but those for GPUs, RAM, and other components require you to look carefully at whether the block fits your specific model of hardware.
A Radiator With Fans: Sold as a single unit, radiators come in multiple sizes and contain differing numbers of fans. More fans means they can dissipate more heat, but it also makes them louder. Two 120mm fans is standard, but you can get radiators accommodating a single fan or up to four. They’re usually mounted internally but can also be mounted externally in smaller cases.
A Reservoir: These allow you to add liquid into the loop, and help you bleed out air bubbles that reduce the efficiency of the cooler. Most of them are mounted inside your case using brackets that are provided, but some can also fit inside existing drive bays.
A Pump: This keeps the water in your cooler moving. Sometimes pumps will come integrated into a reservoir, but it’s also possible to buy them separately. If you do buy them separately, make sure the two use a compatible interface.
Fittings: Fitting allow you to connect tubing to components, so you’ll need some for every separate component: the pump, the radiator, the waterblock and the separate reservoir if you have one. They come in several different forms. Barb fittings are cheap but effective, while compression fittings are more expensive but look better and are extra-secure. Fittings allow you to connect.
Tubing: Once you’ve chosen the fittings, you also need to find tubing with the same diameter. You can use smaller tubing for a tighter fit, but this also increases the risk of tearing, so we don’t recommend it.
In addition to this equipment, you also need coolant. Although ‘watercooling’ implies just water, the fluid inside your cooling system contains several additives. It doesn’t even have to be water, although distilled water (never use tap water!) is about as effective as any other and much more easily available than anything specialist.
As well as water, you may want to add a biocide to prevent any algae or mould from growing inside the equipment, or alternatively a kill coil, which is a small piece of silver with naturally antibacterial properties. Anti-corrosives are necessary if you have more than one type of metal in your loop (for instance, a copper waterblock and an aluminium radiator), to prevent the metal being eroded or oxidising, which reduces efficiency and may clog the system. You may also want to add a drop of washing up liquid, which help prevent air bubbles forming.
Some enthusiasts also like to put colouring into their mix, but we’d advise against this. Household colourants can affect performance and, depending on the substances involved, may bind with other additives to create lumps inside equipment that could clog it up entirely. If you want a coloured effect, we’d recommend using transparent coloured tubing.
The Best Prebuilt Coolers
If you want the superior effects of watercooling without the danger of assembling the unit yourself, a prebuilt cooling system is the way to go. There are many different manufacturers who create such hardware, but these are the best we’ve found.
Fractal Design Kelvin Coolers
Fractal Design creates a huge variety of cooling products, from cases designed with cooling in mind to low-heat PSUs, so its new watercooling line incorporates expertise from all different areas of desktop heat management. Its first set of all-in-one watercoolers contains three different products, all of which incorporate heat blocks and radiators made of pure copper, a low-noise ceramic-bearing 2400rpm pump, and Fractal Design Silent Series fans.
All Kelvin watercoolers are compatible with every major CPU socket out of the box, and although they appear sealed, they can be easily expanded to cool additional components. They feature two-part brass fittings to ensure secure assembly, and they come with all necessary hardware and mountings to get started, making them an excellent choice even if you’re just starting out with watercooling.
The Kelvin T12 is the simplest of the three, with a single 120mm fan. Its cooling is superb, but the single-fan design makes it more of a CPU fan replacement than a way to step up your cooling. Like all singlefan designs, it’s best purchased if you’re more interested in reducing your system’s noise more than its operating temperature (for instance, within an HTPC or file server).
The Kelvin S24 has a similar design but comes with a dual-fan radiator instead. A strong all-rounder, the noise levels are good considering the double-fan design, and the cooling it can offer is far greater than a standard CPU fan can provide. Ideal for overclockers, gamers and other heavyload systems that need their CPUs kept aggressively cool.
Finally, the Kelvin S36 is a three-fan version aimed at heavy-load systems or those who want to cool multiple components with a single radiator. With three fans you can bet it isn’t going to be quiet at high loads, but at the same time, its cooling is efficient, robust and far better value than trying to cool multiple devices with several different coolers. A great choice for even the most precise enthusiast.
Prices for Fractal’s line start at £74.99, which is higher than entry-level but still good value considering the hardware on offer here.
RaiJintek Triton Cooler
Priced around the same amount – you can pick it up for £71.99 from Watercooling UK – the RaiJintek Triton cooler is aimed at gamers who want their cooling system to look as good as a gaming PC should. As well as including an LED illuminated reservoir, the kit comes with four supplied liquids, each a different colour so you can choose the one that works best for your system’s interior.
A double heat exchanger and highperformance aluminium radiator is paired with two variable-speed 120mm fans for superb performance even under heavy loads. The loop can be customised with additional components, but its out-of-the-box performance is impressive. It’s a mid-level piece of hardware aimed at users who aren’t necessarily ready to build their own loop but who want something more flexible than the closed-loop designs of cheaper coolers.
Compatibility extends to all major CPU designs, and the kit itself includes all necessary components, including mountings and thermal gel. For a firsttime cooler it’s probably a little complex, but if you’re looking for something as versatile as a self-build without the hassle of choosing and sourcing components, it’s definitely a strong choice. We’d recommend it for slightly more advanced users who are looking for their second watercooler, as well as first-timers who already have a lot of technical knowledge and don’t want to get boxed in by a standard all-in-one loop.
Corsair Hydro Coolers
If you’d prefer a cheaper all-in-one cooling unit, the Corsair Hydro line is one of the most reliable and established in the field. Unlike the Fractal Design and RaiJintek coolers, they’re not modular or customisable, so you can’t expand them, but this does mean that they’re priced a lot lower. Again, they’re compatible with all major CPU types.
The Corsair Hydro H55 is specifically good for small cases, with a singlefan design that should fit into even a cramped system. Like all closed-loop units, it’s pre-filled and never requires refilling, so it’s good for users who don’t want to constantly maintain their system. It needs no more attention than a standard CPU fan does. At £50 it’s also a very cheap way to get into watercooling and see if you get on with the technology without having to spend a lot of money and time on the endeavour.
The line also includes larger models, such as the H75 (which has a dual - 120mm fan design), the H90 (which has a 140mm fan) and the H110 (with dual - 40mm fans), all of which cater for systems with varying needs, whether that’s greater cooling, lower noise or restricted space inside a case. Each costs a little more than the last, but they’re all still good choices for those seeking value components or beginners who want to try watercooling out.
So hopefully that answers the most pertinent questions about what watercooling is, how to get started and what you can do with it. All that’s left for you to do is get out there and give it a go!