Water Cooling 101: Everything You Need To Know
20 December 2016
Updated for 29/01/2021
Water Cooling 101 All You Need to Know
The PC continues to become more and more powerful. More cores and higher performance is welcome, but it often means that cooling requirements increase as well. For most users, a regular air cooler is sufficient, but for a really powerful PC, you’ll want something that’s a step up. Liquid cooling is the answer.
Higher temperatures are part of a feedback loop along with noise but also performance. More capable cooling means lower fan speeds and less noise. Capable liquid cooling helps to keep the boost and turbo functions of modern CPUs and GPUs running at their best. In other words, better cooling can directly lead to better performance. It’s not something to neglect.
What is water cooling?
Simply put, water is a more efficient temperature conductor than air. Water has the ability to absorb more heat from the block, and in turn, be cooled down as it passes through the radiator. Water cooling systems typically run quieter as a result, though if you’re prepared to push the fans speeds, water-cooled systems are capable of dissipating a lot more heat, making them ideal for overclocking. Let’s face it, a quality water cooled system looks awesome too.
Liquid coolers can take the form of a simple 120mm all in one cooler or go all the way up to a sophisticated custom loop with blocks cooling your CPU, graphics card and motherboard. If you are super keen, or perhaps a little bit crazy, you can also water cool your RAM and even an NVMe SSD!
The purpose of this article is to guide you through the ins and outs of water cooling. There’s a lot to consider and your choice of liquid cooling will depend on exactly what you want from your system as well as your budget. Do you want something affordable? Something quiet? Something to tame a high-end gaming PC? Or perhaps you want a stunning RGB showpiece that will be the envy of anyone that sees it? Read on as we take a deep dive into the world of liquid cooling. Everything you need to know is right here!
Understanding Thermal Design Power (TDP)
Let’s begin with some background and explain why liquid cooling has moved from a niche application to a widely adopted mainstream one. It all comes down to inter-generational increases in power consumption and therefore, heat output. Part of this is due to an increase in core counts but also the prioritising of performance over power consumption. All CPUs and GPUs come with a so-called Thermal Design Power rating, better known as TDP. TDP can be thought of as the amount of heat that the cooler needs to dissipate under default operating conditions. TDP is not the maximum power consumption of the chip, a common misconception.
A 10th Generation desktop CPU from Intel usually comes with either a 65W or 125W TDP rating. AMD CPUs come with similar ratings of 65W and 105W for its Ryzen 5000 series. The general rule of thumb is that a higher TDP means higher cooling requirements, but as with many things in life, it’s not quite so simple. TDP is very much a baseline rating as many products will dissipate a lot more than their official rating suggests, even under 100% default operating conditions.
Let’s use Intel’s 10th generation Core i9-10900K as an example. It has an official TDP of 125W, but this is only under its non-turbo state of 3.7GHz with all cores loaded. This base 125W rating is known as the PL1. But as you’d likely know, Intel CPUs will ‘Turbo Boost’ to much higher frequencies for short durations. When it does this, power consumption is allowed to rise to up to 250W for the 10900K. This is the PL2 limit. Motherboard makers can stretch these limits though. A default 10900K can consume more than 250W or run at the PL2 level for longer. Considering all this, it becomes obvious that liquid cooling is useful not just for keeping your CPU or GPU cool, but also to keep it boosting to the higher turbo or boost frequencies so you can maximise performance.
The following tables approximate what kind of cooling capacity is appropriate for Intel 10th Generation and AMD Ryzen 5000 series CPUs. Of course, there’s nothing stopping you from running a 360mm AIO with a basic quad-core CPU. It would be overkill, but it will definitely be cool and quiet! What you don’t want to do though, is run a 120mm cooler on a high core count, high TDP CPU, especially if you intend to overclock. Even a 240mm cooler will struggle under that kind of scenario.
Why go with water cooling over air cooling?
The simplest explanation is that water cooling is a far more efficient way of dissipating heat (from the water block) and then cooling down again (after passing through the radiator). Air is a relatively poor temperature conductor and it heatsinks lose efficiency over time due to dust build up.
There are other reasons to go with water cooling. A major one is aesthetics. A well designed water-cooled rig is a thing of beauty. If you’ve ever seen a bunch on display at a trade show, they really do generate some serious attention.
A well designed water-cooled rig can also be virtually silent with the right parts. A screamer blower style GPU cooler is seriously noticeable and annoying, and getting rid of that outdoor leaf blower noise is a primary motivator for many liquid cooling enthusiasts.
If you’ve decided to make the jump to liquid cooling, the first purchase you’re likely to consider is that of an all-in-one water cooler, or AIO. An AIO is fully integrated and easy to install water-cooling system. It has the pump integrated into the waterblock itself with tubes connecting to the radiator. The AIO head will have outputs that connect to the motherboard for things like PWM fan control, RGB control and pump speed control. Some AIOs have a lead that connects to a USB header which allows for things like diagnostic and monitoring functionality as well as things like custom profiles and ARGB integration. Some even have displays on the head itself that can show things like the CPU temperature.
AIOs are usually available with four radiator sizes, 120mm, 240mm, 280mm and 360mm though there are exceptions. The numbers refer to the total diagonal diameter of the equipped fans. For example, a 280mm radiator will use 2x 140mm fans or a 360mm rad uses 3x 120mm fans. The cooling capability of an AIO increases with a larger radiator size due to having more surface area for dissipating heat.
AIOs with a 120mm radiator don’t really offer much over an air cooler and in fact, a quality air cooler will outperform it. If you’re running a budget CPU in a regular ATX case, you’d be advised to stick to air cooling. There are scenarios where a 120mm cooler is advantageous though. If you’re building a system with a low TDP CPU in a compact case that won’t fit a large air cooler, then it makes a lot of sense. A 240mm or 280mm cooler should perform at least on par with the best high-end air coolers while a top-spec AIO with a 360mm radiator will outperform even the largest and most expensive air coolers.
Introducing Custom Water Cooling Loops
What if you want to go all the way and water cool not just your CPU, but your GPU and possibly other components as well? While there are a handful of AIO equipped GPUs, if you want to water cool both, you’ll need to consider building your own custom loop. Where an AIO is a simple, easy to install system, a custom loop is a great deal more complicated. But, its advantage is that it’s a lot more effective, it looks fantastic and it can be tailored to suit your system and case. If you really take pride in your PC, a fully water cooled build is something you will surely be proud of.
Before you hop onto the Mwave site and start adding components to your cart, you need to take time and plan out what your loop will consist of as well as things like case considerations, dimension and fittings, especially if you’re cooling multiple components. Plan plan plan. It will remove a lot of headaches later on.
Parts of a water cooled PC
A basic water cooling loop will consist of:
- CPU and/or Graphics Card Water blocks
- Radiator and Fans
Take care to consider how long your tubing needs to be or whether you want flexible or rigid tubing. Your choice of components will depend on the CPU itself and the motherboard, and whether you plan to include a GPU in the loop, or add it later. A simple drawing of your system can help you to visualise things like tubing lengths, depths and dimensions. There’s a lot to consider!
Water blocks are available for different PC components including:
|Removing the heat from the processor into the liquid that runs through the water block|
Removing the heat from the graphics card into the liquid that runs through the water block.
There are two main types of GPU water blocks: full cover blocks and universal blocks for custom graphic cards. While the full-cover block only matches one particular graphic card, the universal GPU block can fit in almost cards.
Removing the heat from the motherboard into the liquid flowing through the water block.
Chipset blocks and monoblack are the two main versions of motherboard water blocks.
There are a few things to consider when choosing a water block. Many motherboards (mostly high-end ones) have specially designed full cover blocks and this may be an option for you. Another thing to consider is whether you want RGB lighting, acrylic or plexi construction to show off coolant colouring or something like a chrome-like nickel finish. EK even make a water block with a walnut finish!
Buying a block for a GPU can be a little more complicated due to the myriad of different custom PCB designs. It’s important to cool not just the GPU, but the VRM and memory too. This is especially important with current high-end GPUs that can easily run well over 300W, meaning the VRM has to work hard, in turn requiring active cooling. This limits universal compatibility and it explains why there are many more custom designed GPU water blocks these days. Don’t forget that it’s also possible to buy pre-assembled cards that ship with water blocks. It’s also possible to buy hybrid GPUs with AIO cooling attached.
You can also buy blocks for cooling just about every other component in your system. Water cooling things like your RAM, SSD or motherboard VRM can be considered optional. As long as you have decent airflow over these components, they will be fine. Things like the motherboard VRMs are designed to run at high temperatures and most motherboards come with quality heatsinks. At least most of the ones that are likely to be included in water cooled systems that is!
A reservoir is used to fill the loop and store extra coolant. It holds air that gradually gets pumped through the system, particularly from the radiator where tiny air bubbles tend to gather. Some manufacturers integrate the pump and reservoir together. Some users like to have the reservoir stashed away out of sight for a cleaner build.
Reservoirs are available in a variety of shapes and sizes. Some can be attached to case fan mounts like you would a radiator, while others are compact and some can even be placed in available 5.25" drive bays. Your choice of reservoir will strongly depend on the case you’re using.
Most brands’ pumps are based on tried and true proven designs from Liang, with two models commonly available, the D5 and the DDC. Many water cooling enthusiasts will offer different opinions on which is best.
D5 based pumps have been battle-tested over many years in high-performance PCs with one or more blocks. They have a high flow rate and are larger and run cooler. They also tend to be favourites of builders who place emphasis on silence due to their low noise characteristic. DDC based designs are more compact and produce a higher pressure, but this makes them a touch noisier and they tend to run a bit hotter. Either one is a safe option, but in the end, your choice may come down to how much space you have in your case.
Some reservoirs come with a pump attached or built-in. This design can be easier for installation but makes it hard if you want to hide the pump or reservoir out of sight. When installing the pump, it is best to keep it now the bottom of the water cooling loop to avoid air entering the pump.
Now, let’s talk radiators. To break it down, buy the biggest one that will fit in your case. A bigger radiator means it has a larger surface area, which means it’s able to dissipate more heat. Similar to AIO radiators, they tend to come in sizes relating to the size and number of fans you can attach to them. Custom water cooling loops also have the ability to add multiple radiators for added cooling, though your chosen case will dictate exactly how large and how many radiators you may use. Some cases may even be designed for mounting a radiator (or radiators) externally for improved compatibility. A 120mm rad is alternately called a single rad, moving up to dual, triple and quad rads, where a dual rad has two fans attached, and so on.
Radiators are available with different thicknesses. This is another way to increase the surface area of a rad. A longer rad is generally advisable over a thicker rad, e.g. a 360mm slimmer rad vs a 240mm thick rad. Thicker rads may run into compatibility issues in many cases, where a thick rad may interfere with the motherboard or something like a HDD drive cage. This is another vital reason to plan out your loop before you jump onto Mwave and add things to your cart.
Your choice of fans will generally follow similar criteria to that you would use when selecting any other PC fan. Do you seek high-performance or silence? Or a trade-off between the two? Don’t forget about ARGB control which enables them to blend into the theme of your rig.
Many manufacturers make fans that are designed for use with radiators. Radiators tend to have densely packed fins, so fans that are designed to provide high static pressure are desirable. Fans like the Noctua NF-A12x25 are designed with this in mind. Such fans force air in the intended direction more effectively than a regular fan which can lose air and therefore efficiency out the side of the fan blades.
The other thing to consider is PWM control. These fans allow the system to control the speed of the fans depending on the load. You don’t want them blasting away at idle but then if you’re in a game and your GPU is hitting 80c or more, then you’ll want more speed to compensate. Good quality PWM fans can do this automatically or they can be set via the BIOS or various software applications to suit your specific needs. A user in Alice Springs might need to crank things up a little more than a gamer in Hobart.
It’s also important to note that a water-cooled system doesn’t provide airflow to adjacent components that an air cooler inherently would, such as the motherboard VRM or even RAM. The need for good case airflow is still important, even if your CPU and/or GPU are lovely and cool.
Soft tubing is obviously easier to work with. There are many different types available including clear, coloured or UV reactive. Hard tubing is usually viewed as the ‘ultimate’ in loop design as it tends to look cleaner and more organised. Hard tubing is considered an advanced loop building method due to its relative difficulty to work with. Don’t forget to plan! The last thing you want is to realise your tubes are too short.
Hard tubing requires a little work to shape and bend it according to your demands. It’s really not difficult and there are several tools that can help to make the job easier. The tubing needs to be heated so it becomes malleable. You’ll need a silicon insert like this (depending on the diameter of your tubing). This keeps the internal diameter of the tube the same as it was before bending and will help to avoid kinking.
The next step is to bend the tube into the shape you want. There are tools available for this too, such as this one from EK. Once again though, it’s important to make sure you get the right diameter tools or inserts to make sure the job is done right. It’s worth checking out one of the many tutorials online if you’re a little uncertain of what to do. This one from Gamers Nexus is a good example.
Your choices of compression fittings will firstly be determined by whether you are using soft tubing or hard tubing. These days almost all water cooling tubing, connections and fittings use a G1/4“thread (12.9mm wide) size. Be sure to confirm compatibility between your waterblocks and tubing when selecting your fittings.
If you’re building a serious water cooling system, you’ll need a load of fittings. All those tubes, blocks, radiators, reservoirs and pumps need to be securely connected to one another. This perfectly illustrates the importance of thoroughly planning your build in advance. And don’t forget to order a spare or two as you don’t want to be caught one short!
Mwave carry a full range of fittings in all different shapes, sizes and colours. Again, make sure you match them to the rest of the loop. Having the wrong kind of fitting is a showstopper. Don’t forget you’ll need to drain the loop eventually, so some kind of drain port is advantageous.
Coolants and additives
The warm liquid of a water cooling system is a natural breeding ground for bacteria, algae and other nasties. The metals in water cooling systems are also prone to corrosion, especially if a mix of metals are used within the water cooling loop (e.g. copper and aluminium). A few simple steps will go a long way to keeping your cooling healthy.
Never use tap water in your system. Even distilled water alone will not protect your system. It’s important to use a specialised cooling solution. These are available in either concentrate or pre-mixed form. They are specifically designed for water cooling and come in a range of colours. They’re designed to prevent biological growth and include corrosion inhibitors.
The colouring of your system is one of the fundamental decisions you will make. Mwave offer a full range of coolant in a variety of colours.
Putting it all together (and showing it all off!)
Now comes the fun part, or is that the worst part? Putting it all together! If you’re used to building PCs, a lot of it will be second nature. With any luck, the plan you formulated right at the beginning will have come to fruition. Things like your tube lengths, fittings, component location and block installation will have come off without a hitch. Don’t forget to grab some thermal compound too.
The water cooling loop order generally doesn’t matter too much in systems where the flow around the loop takes just a matter of seconds. The days of SLI and Crossfire are pretty much over and a good D5 pump will circulate liquid across a GPU & CPU waterblocks or CPU + motherboard monoblocks effectively.
After assembling the system, the time comes to fill it and test for leaks. There are many methods. There are a lot of guides on YouTube if you’re unsure of how to go about it. You can do it without filling thanks to a handy pressure tester such as this EKWB leak tester. However you do it, the primary consideration is protecting your system from damage, so always take care. Placing some paper towelling around the connectors and under fittings will quickly reveal a leak. You could consider a 24-pin PSU jumper cable so that only the pump receives power from the PSU. That way you can fill the reservoir, power up the pump until the reservoir gets low, and fill it again. It’s very important not to let the pump run dry. Filling the reservoir with this filling bottle will make life a bit easier.
Now that you’re put it all together and have filled the loop, it’s time to fire up the system. This can be a moment that includes nerve-wracking anxiety through to relief and exhilaration! It’s always a great feeling seeing the system that you put your blood sweat and tears into fire up for the first time. Now is the time to get into your system's RGB controls and calibrate them just the way you like. Uploading pics to your social media will surely elicit many oohs and ahhs!
How to maintain your water cooled PC
From time to time, you will need to perform some periodic maintenance on your custom liquid cooling loop in order to keep it fully functional and healthy. Maintenance is a critical preventative measure to minimise the chance of leaks and corrosion + it will help to keep your loop performing its best. If you notice build-up of gunk in a pastel cooled loop, liquid discoloration or a loss of cooling performance, then the best bet is to pull it all apart for a clean.
The first thing you’ll need to do is drain the loop. This can be done via the reservoir if there’s a port, or by a dedicated drain port. Once it’s drained, you can inspect the components themselves, this includes the fittings, tubing and everything else.
Cleaning is highly dependent on the component. You can use distilled water to flush the loop, this should remove loose particles in the system including leftover coolant and colouring. This is particularly important if you want to change the colour, particularly if it’s a pastel based colour.
The method used for cleaning a block depends on what it’s made of. For copper you can use something like lemon juice (it’s slightly acidic) whereas you’d use normal water for a nickel block.
Additionally, thanks to evaporation caused by heat-cycles in your custom liquid cooling loop, you may need to top-up your coolant via the reservoir every few months.
Enjoy your new cool and quiet rig. Be amazed at the low temperatures, but try to keep your eyes on the screen! Whether you’re gaming, creating or just browsing. We’re sure you’ll be casting an eye over at your labour of love all too frequently.
Mwave are the water cooling specialists, so please don’t hesitate to get in touch with us if you have any questions or need advice on planning your ultimate water cooled dream rig.