The Ultimate Guide to Custom Watercooling your PC

Liquid Cooling your PC components can be a great way to extend their longevity and performance. Our Ultimate PC Watercooling Guide will show you to get setup.
by Andy Cresswell -
The Ultimate Guide to Custom Watercooling your PC

Liquid cooling your CPU and other components can be a gratifying experience not only for your self-confidence as a PC builder or enthusiast but also increases the longevity of your overclocked components in the long term.

Would you believe that, until last month, I ran the same CPU and motherboard running at 5.2ghz 24/7 while compiling development code and playing games for almost a decade? The only reason I could do that was because of my custom water cooling loop keeping everything at decent temperatures – I didn’t even change the coolant once in that time.

Over the course of this stupidly long custom PC watercooling guide, you will become a watercooling GURU. Armed with enough information to make an informed decision on the components you will need to buy to watercool your gaming PC.

Common Questions

There are a lot of questions I get asked that I find myself repeating so I put them all together here. Hopefully, these common PC watercooling questions and answers can clear up any confusion you may have.

If I missed something out, let us know in the comments and we can answer your question.

What is PC Watercooling?

An overclocked, watercooled PC
Custom Test Rig with A Fully Custom Watercooling Loop by PPSU

PC Watercooling or as it is also known, Liquid PC Cooling, is a form of extreme pc cooling which come about because of PC enthusiasts and PC gamers constant need for more processing speed and frame rates. liquid cooling loops consist of a pump, radiator, watercooling block and hard or soft tubing.

There are several types of liquid cooling builds available on the market;

  1. All-in-one CPU/GPU Watercooling Units – These units are sealed and not intended to be serviced. They offer marginally better performance than air CPU coolers in most cases.
  2. Custom Watercooling Kits – entry-level kits can be a great way to get into watercooling however, in most cases, cooling capacity is limited by smaller radiators. Great for single component builds but not if you want something to keep your gaming PC cool
  3. Fully Custom Liquid Cooling – These custom liquid cooling systems are tailored exactly to your requirements but require you to do a little bit of research first. Normally comprised of custom cooling blocks, multiple radiators and a high-end powerful pump. These custom loops can go on for years simply by upgrading the water blocks.

Overclocking was a big driver in the development of extreme cooling solutions for PCs, and, became mainstream when bios based overclocking become the norm over jumper-based configurations that only allowed for adjustments to the front side bus (FSB).

Why is CPU Watercooling Better Than CPU Air Cooling?

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A watercooled gaming PC built by PerformancePSU

CPU Watercooling is superior to CPU air cooling in most instances. This is due to the larger surface area of a watercooling loops radiator vs the surface area of a traditional air solution which is much smaller.

Water effectively transfers the heat away from the components and dissipates that thermal energy across the fins, allowing the fans to remove the excess heat from the system. This is why water cooling your PC can used to keep components cooler than traditional air-based solutions under extreme stress situations. Consisting of primarily a CPU block, water pump, reservoir and radiator, watercooling is a form of extreme PC cooling that carries heat away from components more efficiently than air.

The cooling power of a particular water cooling loop is always dependent on the parts selected for the build. For example, If you have been planning to use a small 120mm radiator with some spare fans you have in the cupboard, then you might be better off spending the money on a quality air HSF rather than investing in liquid cooling.

Whats Better, All-in-one CPU Watercooling or a Custom Build?

corsair h55 liquid water cooling kit
Corsair All-in-one watercooling

Closed-loop vs custom build PC water cooling is not a straightforward question to answer and comes down to how far you want to push your system and also your budget for watercooling.

The problem with all-in-one CPU watercooling units is that most of the pumps are just not very powerful. They come built into the CPU block, providing low flow through the loop.

Should I buy Hard Tubing or Soft Tubing for my watercooling build?

Ever since hard tubing made an appearance, there has been a burning question in everyone’s head; Do I choose hard tubing or soft tubing for my custom watercooling build? The answer to this question really comes down to aesthetics and the amount of time you have to invest in building your loop and of course, your confidence levels.

Both hard acrylic (sometimes also PTEG) and soft tubing have their advantages and disadvantages as does soft-tubing.

Acrylic tubing brings clarity and beautiful lines at the expense of being tough to work with. Acrylic tubing can often shatter when working with it and its can be challenging to bend and not overheat the material. Generally, hard tube builds take longer to build, have a lesser margin for error and need a tonne more attention to detail.

Soft tubing on the other hand often lacks clarity, is not normally UV light friendly (tubes will often glow and absorb any UV before it hits any pigments in your dye) and lacks straight beautiful lines however, it’s easy to work with, loops are complete fast and they can still look amazing!

The choice is entirely down to you, but, if it was me, I would spend the extra money and time and go for acrylic because I am a sucker for straight lines.

What is the minimum radiator size I need for my watercooling loop?

As a general rule, you will want to assign at least 1 x 120mm per component you are cooling but this comes with a caveat. This would assume you don’t plan on doing any overclocking at all.

What I prefer to do is assign 240mm of radiator space with a push/push fan configuration utilisation static pressure fans. If I have space left over in the build to squeeze another radiator or a bigger one in, I will always do that.

My mantra? go as big as you can and fill up all the space – the result will be an ultra-cool system capable of decent overclocks and near-silent operation (with a fan controller)

Is it worth watercooling my CPU or GPU?

For many, watercooling a CPU, GPU or other components will mostly come down to aesthetics and sometimes noise levels however, if you are a die-hard overclocker looking to increase the lifespan of your components, then, watercooling your PC is definitely worth the investment because liquid cooling is generally more efficient at removing excess heat from the loop.

Is it hard to maintain a watercooling loop?

As long as your loop is sanitary and you use the correct liquid for your watercooling loop, they require almost no maintenance at all. It is recommended to flush the watercooling system with distilled water once every 12 months and refill just to avoid any build-up that may occur.

Is liquid cooling quieter than air cooling?

There are a lot of factors that can affect the noise of your watercooling loop but generally, watercooling is quieter than air-cooling solutions. Radiator fin density has a huge impact on how loud your gaming PC is perceived to be as well as they noise levels of your fans.

A Beginners Guide to Watercooling Components

There is a famous saying that a building without a solid foundation cannot stand, and the same is true for your watercooling loop. Choosing the right parts is crucial to the success of your custom watercooling build and subsequent overclocking efforts.

Let us take a look at all of the various components involved in a custom watercooling loop.

CPU / GPU / RAM Cooling Blocks

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EK Quantum Valocity aRGB CPU Block

Primarily constructed of copper (sometimes silver), watercooling blocks sit on your PC components drawing heat away. CPU, GPU, RAM and Motherboard blocks are doing the brunt of the work in the loop of drawing the heat away from your components to your radiators.

Names to look out for: EKWB, Phankteks, Alphacool and Corsair.

Top Tip: Mounting your blocks at different orientations can yield better results on some CPUs, find out more here


The pump is one of the most crucial parts of any watercooling build, there are lots on the market, but over the years, a couple of specific pumps have stood out from the crowd, consistently performing above the rest.

Names to look out for: XSPC, EKWB (EK DDC, EK-Quantum), Alphacool

Update: I have since invested in a EKWB dual DDC 3.2 PWM pump. It’s great to run them at near silent operating speeds and still maintain a very competitive 24/7 overclock. The added security of have a redundant pump sweetens the deal making sure that if one pump dies, the rest of the system won’t overheat and die.


In short, the radiator is responsible for dissipating heat from your watercooling loop. It does this by spreading heat over its surface allowing the fans to carry the heat away from the loop.

There are a few key points you should be looking at when you buy a radiator;

  • FPI – Fins per inch
  • Size / Thickness
  • Type of metal

FPI or ‘Fins Per Inch’ is one of the things you need to be looking out for when selecting your radiator. Size does play a big role in any radiator’s cooling efficiency, but fin density is equally, if not more, important. The only problem this setup faces is that it can be quite noisy at full chaps due to the use of high-static pressure fans – without them, a high fin-density radiator will perform poorly.

I will always opt to go with more fins per inch and invest in static pressure cooling fans when overclocking as they provide superior cooling efficiency.

Top Tip: If noise is a huge issue for you, then Alphacool’s NexXxos radiators are solid performers and reasonably quiet also due to their lower fin density but of course, this comes at the cost of raw performance.


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EKWB Sidepanel Reservoir with integrated aRGB led lighting

Watercooling reservoirs come in all shapes and sizes but all serve a primary purpose; to provide filling ports for you to keep your system topped up and, in some cases to make your build look insane.

Custom PC watercooling reservoirs are available in a few options.

  • Drive Bay Mounted – These normally sit where DVD drives or Floppy drives used to sit. Drive bay reservoirs have been around for years and are very simple to install and use. They can either come with a mounting bracket to attach your pump or simply with two bars.You don’t see too many of these around.
  • Tubular – Tubular reservoirs have grown in popularity over the past few years. They are simple to install and often have kits available, allowing them to be directly attached to your pump and provide great hydraulic pressure. Best of all, they look absolutely amazing, especially when combined with some Mayhem’s Aurora coolant.
  • Distro Plate – These are relatively new but look amazing. They take over a large portion of the case and serve a dual purpose of both keeping the system topped up but also distributing everything throughout the system.
  • Simple T-line – While a t-line is not strictly a reservoir, A T-line by-passes the need for a reservoir but can be quite tricky for a newbie to bleed the system.


Things soon get confusing when it comes to tubing, especially if you are new to PC water cooling. First off, there are many different dimensions with various inner and outer diameters. Once you know the diameter you will be using, you have to choose between acrylic and flexible tubing; both have their advantages and disadvantages, so choose wisely.

If you are a beginner and this will be your first build, go with flexible tubing the first time around, as it is a lot more forgiving if you do make a mistake.

No matter which tube diameter you decide to go for, your end choice will not affect your loop’s overall performance or temperature only the aesthetics of the build.

Radiator Fans

While you cannot cool anything beyond ambient case temperature without using sub-zero cooling methods, having solid fans that provide enough static pressure will help keep temperatures under control when pushing the boundaries.

Standard case fans will keep your components reasonably cool at idle, but any pressure and heat will start to build up in the loop resulting in high temperatures after prolonged use.

The only downside of using a high-CFM fan is noise. As more air is passing through the fins, it is natural for more noise to be produced; as long as you have a fan controller, it should not be a huge issue.

A great high static pressure fan that is readily available and look great is Corsair’s 120mm and 140mm SP Range. They are shipped with all of Corsair’s AIO Hydro coolers, and I use them on all of my daily systems.

If you don’t care about noise then definitely check out Delta fans, they provide unprecedented performance with some pushing upto 190CFM! they are noisy at full-chaps cranking out 48Dba but grab a fan controller and you will do fine, they really are the best fan money can buy for any serious overclocker.


Pc watercooling parts with pump, reservoir and blocks

There are two types of fixture or ‘barb’.

Compression fitting

A compression fitting provides a smoother build process and looks much nicer; however, if you fiddle around too much in your case, they can come loose and leak. That does not mean they are not safe; you have to take more care when building your system, making sure all connections are as tight as they can be.

Compression fittings are my go-to choice for water-cooling builds. If you have a small case where build space is limited, angled compression fittings can make the whole process easier and much cleaner.

Standard Jubilee Barb

The second type of barb is your standard affair, where the tubing slides over the end and is fastened into place using jubilee clips. As a beginner, this is how I started to reduce points of failure and the potential for leaks. You can get them really tight, making it nearly impossible for any water to leak unless you didn’t screw in the barb tight enough.

Top Tip Generally speaking, each section in the loop will require two barbs, an inlet, and an outlet. However, sometimes pumps come with moulded cases that already have barbs for you to use.

Cooling Fluids

The cheapest water cooling fluid around (and best) is osmosis or distilled water. You cannot just use it straight from the tap because of the high mineral content.

For flexible tubing systems, you must use distilled water and treat the water with a solution that neutralizes the Ph level or even use a silver kill coil that kills bacteria. It keeps the loop free of gunk and performing at its peak.

If you want your liquid cooling loop to glow under UV cathode lighting, then buy tubing that is already pre-coloured and UV treated; it will not fade and will always look vibrant

For people building with acrylic tubing, it is safe to use the huge range of fluids that are premixed with colorants. The hard polymers in the acrylic tubing most colorants in the tubing do not damage the tubing.

Custom Watercooling Build Tips

So your parts have arrived, and its build-time, but where do you start? Let’s run through the checklist; if there is anything you do not have, go to your local hardware store to try to source the parts or order them online! It means a delayed build but will be worth it. After all, you can’t build anything if you forgot a vital PC water-cooling component.

Custom Build Checklist

Everything marked with an asterisk is optional.

  • CPU / GPU* / RAM Blocks*
  • Water Pump
  • Reservoir
  • Tubing
  • Appropriate number of barbs
  • Tubing clips if your are not using compression fittings
  • Mole grips
  • Screwdrivers
  • Flexi-tube cutter
  • Thermal Paste such as Artic Silver 5

If you mentally checked yes to all of the above, let’s get started.

1. Watercooling Loop Order

One of the most asked questions, even amongst the pros, is what the best water cooling loop order is? The truth is that temperatures throughout the loop will only vary +/- 1*c at any one time and will not make or break a record-breaking overclock. My advice has always been to set it up however it looks best with one exception –

The only requirement when you are constructing your loop is to make sure the reservoir is feeding the pump (and positioned above); it will make bleeding the system easier, but it will prolong the life of the pump.

A dry pump is a dead pump!

2. Leak Testing

Leak testing may seem like a tedious, unnecessary step. After all, you fastened up your compression fittings or jubilee clips as tight as they will go – “It can’t possibly leak” but trust me when I say those are the famous last words.

When you first build the loop, do it inside the case. Then once completed remove all the components and use the paper clip PSU trick to get the water pump running directly without anything else plugged in.

Even after you leak-tested and put your components in, it is always wise to monitor the situation, pad barbs and the top of the graphics cards with kitchen paper and make sure no further leaks have appeared. When moving tubing around, sometimes it can dislodge the barb and make it loose, resulting in a small leak that gets worse and worse – be safe and double-check everything.

3. Do things up tight but don’t overdo it!

A mistake plenty of people have made before and only applies to leucite top cooling blocks and reservoirs.

If you over tighten your barbs, there is a huge possibility that you may end up cracking your CPU block or reservoir. It is easily done, so take your time.

When using compression fittings, remember to allow some when you are securing your tubes into place. As you tighten them up, the barbs will slightly tighten as well.

4. Use the correct screws for your radiator

Using the correct screws is so important when fixing your fans onto your radiator. If the screws are too long, its possible to puncture the radiator and cause a leak.

Many manufacturers have moved cooling lines further in as well as putting blanking plates below the screws to stop this from happening. Still, if you are on a budget, many radiators do not factor this into their design.

5. Don’t neglect case airflow

Never underestimate the power and importance of quality airflow through the case. It does not just apply to people cooling on with air alone, but to us, the watercooler’s airflow is vital to keeping temperatures down and stable.

Even if you are cooling all the components in your case, they will still generate heat. Heat will build up in the case (and around your radiators), increasing the ambient case temperature and reducing your radiator’s cooling efficiency.

6. Take your time bleeding the system

Bleeding your water cooling system takes patience and can often be frustrating but getting every air bubble out of the loop. Still, it’s an essential step if you want consistent temperatures.

It’s not uncommon for there to be a +/- 10*c temperature difference between cores if there is air trapped in the loop or there is not enough (or too much) thermal compound.

There are a few tips that can help bleed your loop easier and reduce the beads of sweat accumulating on your brow. Bleeding your water loop does not have to be a stressful experience if you are pre-armed with some tips!

  1. Always make sure the reservoir is feeding the water-cooling pump and is not letting any air into the pump
  2. Turning the pump off and on periodically will allow the smaller bubbles to become bigger bubbles that help to flush through easier
  3. When the loop is 3/4 full, gently rock your PC case back and forth to dislodge air bubbles
  4. Squeezing the tubes and releasing helps build up extra pressure in the system, helping to flush it through
  5. Smile, it’s proven to release happy chemicals in our brain that combat stress!

7. Do not mix and match different metals in your custom PC watercooling loop

Over the years of building and hundreds of hours spent on forums, one thing I have consistently read is you should never mix metals. This is because they can react with each other causing galvanic corrosion, while it’s not a huge problem with modern loops you should definitely learn a little about it..

Galvanic corrosion is an electrochemical process in which one metal corrodes preferentially to another when both metals are in electrical contact, in the presence of an electrolyte. This same galvanic reaction is exploited in primary batteries to generate an electrical voltage.


The result of galvanic corrosion in a water cooling loop can be devastating, causing irreversible damage to your water cooling loop and your PC components.

How to Put Your Custom PC Watercooling Together

Putting your custom PC water cooling loop together for the first time can seem like a daunting thing, but it is not and quite straightforward when you know how. As with all things, organization is the key.

Step One: Assemble Blocks & Add Fittings

Depending on what water block you brought, you may or may not have to construct it. My EKWB Supreme-HF come pre-constructed for me however, it did come with instructions so you can do it yourself just in case you need to clean it in the future.

When attaching your barbs, make sure they all include their rubber washers. Sometimes they go astray in the manufacturing process; if one is missing, the loop will spring a leak.

Step Two: Attach Cooling Blocks

Before rushing ahead and putting everything in the case, it’s always handy to attach the brackets and the CPU block to the motherboard (and other components, if applicable). Your knuckles do end up feeling the full extent of the case’s wrath if you try to attach them when the motherboard is already mounted. It also allows you to evenly fasten the CPU block to the motherboard resulting in a perfect thermal compound application.

Step Three: Mount the Radiator

If you have a slimline radiator such as Hardware Labs Black-ice 2 stealth, this step is not as important. Still, if you have a really thick radiator, it can be fiddly to get the motherboard mounted, especially if you are mounting it on the inside top of your case.

Go ahead and get that bad boy mounted!

Step Four: Install the reservoir & Pump

Depending on what reservoir and pump you bought, they may or may not be combined. Your job is to get the pump and reservoir both secured into place, visually plan where your tubes will go and try not to have them extend across the case.

It reduces the flow in the system and takes longer for cool water to return to the CPU.

IMPORTANT! If you are using a 5’25 drive bay reservoir, make sure to leave yourself enough clearance to fill it up

Step Five: Install Components into the Case

With all the bulky stuff installed in the case, now is a great time to install all of your components, don’t worry about tubing; that is the next step!

Step Six: Cutting Tubing to Size and Fasten in Place

If you are using acrylic tubing, take your time. It is not forgiving if you cut your tubing too short not only do you waste money, but the immense time you spent heating and bending the tubing.

Step Seven: Bleed & Leak Test

Remember the tip before about how important leak testing is? I will say it just one more time – Don’t skip this step.

Remove your PC components out of the case and gently rest them on an anti-static bag on top of your motherboard box for now. Fill up the reservoir and use the paperclip trick to start the pump; remember to keep the reservoir high in the loop and make sure no air enters the loop.

You may need to turn the pump on and off a few times to force air through the system, and it allows all the smaller bubbles to accumulate into bigger bubbles allowing them to pass through the loop easier.

When the pump stops making a gurgling sound, the water-cooling loop is full, but it still helps to rock the case gently to move any stubborn bubbles.

Step Eight: Final Build

So 24 hours have passed, and no leaks have sprung. Great news! You can now put your PC components back into your case, add thermal compound to the CPU and secure the block in place.

Remember, even after you have leak tested and put your components in, it is always wise to monitor the situation for an hour.

Ensure all your barbs are tight and not freely moving around. It’s still possible to dislodge barbs.

Take Home

There is a lot to learn initially when your start out water cooling but once you have done it once it’s easy to do it again. With the above PC water cooling guide you should now know enough to go and build you’re own just remember:

  • Research, research, research – it will pay off in the end
  • Only use distilled water in flexi-tubing systems
  • Never skip leak testing
  • Don’t mix different metals in the watercooling loop
  • Strike the right balance between radiator FPI and size
  • Take your time, don’t rush

Do you think I missed something out of this custom water cooling guide? Let me know in the comments, and I will make sure I get it amended right away.

Don’t forget to come and show off your custom water cooling builds in the comments section below.

Avatar for Andy Cresswell
Andy Cresswell

PerformancePSU Editor

Andy is the Founder & Editor of PerformancePSU with over 25 years of experience building custom PCs, watercooling and overclocking. When his thirst for more speed is under control, he is a programmer and father of one.
Reader Comments
  • isnt this jaystwocents computer thats called SKUNKWORKS ???

  • Water cooling is better for a 24/7 rig as long as any radiators are outside the case as it more effectively moves heat away from all the components. Decent cooling is important for the vrms and northbridge as they will quickly degrade without, stock coolers cool these parts along with the CPU.
    Air cooling with top quality heatsinks is better for over clocking rigs that are not housed inside a case as they can remove heat into the air instantly without relying on a pump.

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