Liquid cooling - everything you need to know

Liquid cooling systems are increasingly a claim not only for gamer enthusiasts, but for less advanced users and fans of modding. Despite being seen as more decorative than a heatsink, these are generally much better cooling systems than heatsinks.

In this article we will see everything you need to know about this PC component. Maybe we convince you that having one gives good advantages in case we have a powerful computer.

What is liquid cooling and how does it work

We will all know or have ever seen our CPU cooler, an aluminum block with a fan on top. Well like this, a liquid cooling system serves to remove heat from the processor, and not only from this, but also from other hardware such as the graphics card, RAM or VRM.

Mind you, the operating foundation is quite different from an air sink. These systems are made up of a closed circuit of distilled water or any other liquid that can be used. This liquid remains in continuous movement thanks to a pump or a tank provided with a pump so that it passes through the different blocks installed on the hardware to be refrigerated. In turn, the hot liquid passes through what is essentially a radiator-shaped heat sink, more or less large, provided with fans. In this way, the liquid cools down again, repeating the cycle indefinitely while our equipment is running.

Just like in a heatsink, the liquid cooling system relies on two principles of thermodynamics to work, and a third of fluid mechanics.

• Conduction: conduction is the phenomenon by which a hotter solid body passes its heat to a colder one that is in contact with it. This occurs between the cooling block or cold block, and the CPU, the IHS of the processor passes heat to the block through which fluid will then pass to cool. Convection: Convection is another phenomenon of heat transfer that occurs only in fluids, water, air or steam. In this case, convection acts on the moving water in the circuit. On the one hand, the CPU block transfers heat to the fluid, increasing its temperature, and on the other hand, the radiator removes this heat through its channels and fins bathed in an air stream generated by the fans. Laminar flow: Fluids have two types of movement regime, laminar and turbulent. In this case it is always intended that the flow is laminar, more orderly and that it is capable of absorbing more heat by convection.

Measurements and magnitudes

After the fundamentals of the operation, it is convenient to know what are the magnitudes that we should know about the components of liquid cooling. As with fans or heatsinks, there will be more and less good components.

• Noise: the pump is an element that has a motor, so it will also generate noise when operating. It is measured in dBA. RPM: Like fans, a pump will have its certain revolutions per minute. In addition, they always have PWM or Analog control. Flow: the fluid flow is measured in L / h (liters per hour), the higher this is, the more cooling capacity the system will have. Pressure: Pressure is the force exerted by the liquid on the walls of the tubes and dissipation components. It is measured in bar (bars) Pumping height: in custom systems an important parameter of the pump will be the maximum height at which the fluid can be pumped. In this way we can mount the system and ensure that the liquid reaches the highest areas. Area and format of the radiator: the cooling capacity of a radiator is determined by the maximum area it covers, both in thickness and in length and width. It is measured in m ², and the more, the better, of course. Conductivity: all components, be they fluid or blocks, have thermal connectivity, which is their ability to transport heat without resistance. It is measured in W / m * K (Watts per Kelvin Meter). The idea is that this conductivity is the highest possible in each element. Typical parameters of fans: among the typical parameters of fans we have its static pressure, measured in mmH2O and its air flow, measured in FCM. We have all this information in the fans article: everything you need to know.

Liquid cooling types

In the market we can find mainly two types of liquid cooling, all-in-one systems, and custom systems.

All-in-one or AIO systems are basically circuits that are already completely assembled by the manufacturer with everything necessary to install and operate. In general, they are much cheaper than the following ones that we will see, although they will only be able to cool the processor thanks to a single block with an integrated pump, a radiator and its tubes installed in a fixed way and the fluid already introduced.

The second type of liquid refrigeration is the personalized or Custom, which by discard we will understand that we will have to assemble it ourselves piece by piece. In them, the components come all separately, and in the quantity that we have ordered. For example 3 meters of tube, two cold blocks, a tank, two radiators, etc. In this way the circuit adapts perfectly to our chassis, with the components that we want to cool and with the design that we deem appropriate. These Custom systems feature blocks to cool even VRM RAM memories or hard drives.

There is still a third method of liquid cooling that is immersion. Here what is done is to immerse all the electronic components inside a container with a fluid that is not conductive of electricity. These fluids are generally oils, which do not have electrical conductivity. In them, a pumping system keeps the liquid moving so that convection is more effective.

Components of liquid cooling

Let's take a closer look at the different components involved in liquid cooling. In general, all systems are based on the same components, although we can see certain variants or a greater number of some of them.

Coolant fluid

The cooling fluid is the element in charge of carrying the thermal energy from the components to the radiator. Normally a fluid with good conductivity and medium viscosity should be used to avoid turbulent flow. The most distinguished manufacturer of cooling fluids is Mayhems, which has a wide range of liquids for custom refrigeration, although it also supplies other brands such as Corsair with its Hydro X.

The most commonly used fluids are normally derived from ethylene glycol, or simply glycol. This is an organic chemical compound made from ethylene oxide, so it is certainly toxic. It is presented with a higher viscosity than water, being colorless and odorless, which is why color additives are normally added to help differentiate it from water. This compound is mixed with distilled water or other supplements to form the mixture, and having a boiling point of 197 ⁰C makes it ideal for coolant, car or these systems that we see.

However, in all-in-one systems, the fluid normally used is distilled water, or pure water, which has good thermal performance and is not electrically conductive.

Pump and tank

The pump is the element that makes the liquid move throughout the circuit, if it would not be possible to transport heat from the electronic components to the radiator. In all-in-one systems this pump is normally located directly in the cold block, in order to simplify the circuit and optimize the space occupied. In these systems, changing the fluid is a bit more complicated since we must purge the system well so that there is no air inside that worsens the circulation.

On the other hand, in customized systems they alleviate this problem of purging the system by means of a tank that integrates the pump. Let's say it is like the expansion tank of cars, an element that contains a large amount of fluid at ambient pressure where it falls from above and below, a pump sets it in motion again. This also prevents the circuit from increasing in pressure due to the expansion of the fluid due to the temperature.

In the market we basically have two types of pumps for refrigeration: the D5 and the DDC with different variants. D5 pumps are generally larger, although the engine turning system is essentially the same on both. A motor with the axis resting on the base where it rotates, which have the magnets that are forced to rotate by the windings or coils placed in an independent chamber so that they do not get wet.

Being larger, the D5 have more flow and lower loudness, although the fluid pressure is lower. These pumps are typically used in custom system tanks. In contrast, DDCs with smaller, more compact pumps that move fluid at higher pressure. DDCs are typically used for all-in-one systems built on the cold block.

Cold Blocks

The cold blocks or cooling plates are the elements that are installed directly on the electronic components that are to be cooled. These blocks can have very different shapes and designs, although it is a constant that they are made of copper or aluminum. They are the two most widely used metals, the first with a conductivity of between 372 and 385 W / mK depending on its purity, and the second with 237 W / mK. Obviously, the higher the conductivity, the better choice it will be, so it is evident that copper is the best option in length, since it is only surpassed by silver and more expensive compounds to manufacture.

These blocks have a solid base that makes contact with the IHS of the CPU or GPU, while internally, a large number of channels pass the liquid through the metal to collect heat. The blocks of all-in-one systems are somewhat more complex, since they integrate the pump there. In addition, some of them even have fins and fans to remove part of the heat already directly from the base itself, thus alleviating the work that the radiator must do.

The good thing is that the manufacturers make available to the user blocks compatible with RAM memory, with the VRMs of the motherboards, for example, the Asus Maximus XI Formula, or for SSD or HDD storage units. The possibilities are enormous.

Thermal paste

But of course, between the CPU and the block there must be a component that improves heat transfer, and this will be the thermal paste. Its operation, application and characteristics will be exactly the same as in normal heatsinks, improving the contact between the block and the CPU.

Radiator

The radiator or exchanger is the component in charge of sending the heat that transports the liquid to the environment. Its operation is exactly the same as any other car radiator or air conditioning, it is a large surface always built in aluminum provided with a large number of channels through which hot water circulates in the form of a coil. In turn, these channels are linked together by a very dense system of thin aluminum fins that distribute heat throughout the surface.

A radiator cannot properly function without a forced ventilation system, so fans are installed on its surface to generate an air current perpendicular to the fins that collect heat through convection. Essentially, two water-metal-air convection exchanges are involved in a radiator.

The radiators used in PC liquid cooling systems are almost always a standardized size, with a width of 120 or 140 mm and different lengths depending on the number of fans that we are going to fit. It can be 120, 140, 240, 280, 360 or 420mm for 1, 2 or 3 120mm or 140mm fans. Likewise, the all-in-ones have a standard thickness of 25-27 mm, while in custom systems we have blocks that even exceed 60 mm for extreme configurations.

Fans

The fans are in charge of supplying the necessary air current to cool the fluid that runs through the radiator. For them, we already have an article where we explain in a very detailed way how it works. Here, what we have to stay with is its dimensions, since we find those of 140 mm and those of 120 mm.

Depending on the capacity of our chassis and the radiator, we will mount one or the other. Of course all AIO systems already include the necessary ones, but we can still do an extra configuration called Push and Pull. That consists of placing fans on both sides of the radiator, some will push the air towards it, and the others will collect it and expel it with greater speed. It doesn't really double the flow, although for thick radiators it might be worth doing.

Tubes

The important part of a liquid cooling system will be the tubes, how could we get the fluid from one place to another without them? Tubes, like other components, usually have a standard section that is 10 mm (3/8 inch) or 13 mm (1/2 inch) for flexible tubes and 10 or 14 mm for rigid tubes .

In the case of AIO systems, we should not worry excessively about them, since they are between 40 and 70 cm in length and come fully assembled in the system. These are almost always made of rubber and covered with textile or nylon mesh to reinforce them. This will allow them to be handled safely without bending or splitting.

Something different are those of the customized systems, since to begin with we will have to buy them separately and with the interior and exterior section compatible with the rest of the joining elements. We have on one hand the flexible tubes, which are usually made of Polyvinyl Chloride (PVC). If advantage is that they are flexible and easy to install, since they adapt quite well to the situation of the hardware, although beware, because they fold very easily. On the other hand, we have rigid tubes also built in PVC or Polymethylmethacrylate, a thermoplastic compound that we will have to heat to give it the proper shape. With the latter, the result of the assemblies is spectacular.

Fittings and connecting elements

And last but not least, we have the joining elements that are used only for custom systems. AIOs already come with everything installed, and the joints are usually made by pressure or with sleeves that cannot be removed.

Instead, to mount the other system we will need the fittings, or unions in the form of elbows, sleeves or dividers to join the pieces of had. These joining elements are normally made of brass, a copper and zinc alloy resistant to water and good corrosion resistance. We can also find them directly in aluminum or copper, and if they are of extreme quality, in stainless steel.

RGB lighting system

And of course, in a liquid cooling system the presence of RGB lighting must be a priority, since it is about our PC being spectacular. In fact, more and more systems include RGB fans and also LEDs on the pump block. And let's not talk about custom ones, for example the Corsair Hydro X, which has RGB in all its cooling blocks, in the tank and in the fans.

Most are directly manageable by software, or are otherwise compatible with motherboard lighting technologies, for example Asus AURA Sync, MSI Mystic Light, Gigabyte RGB Fusion or ASRock Polychrome.

Installation of a liquid cooling

In the case of these systems, the decision is not as simple as that of air sinks, since more factors influence the type of socket it is intended for. In any case, the steps to take are different if it is an AIO or a custom System.

AIO

In all-in-ones, the task will be quite simple, since the system comes fully assembled from the factory and we only have to ensure compatibility with the place it is intended for. These are the factors to consider:

• CPU socket: Obviously we need a block compatible with our equipment, although practically all offer the full range of support, for AMD and Intel. Only the Threadrippers are usually left out on cheaper systems, if we have one of these, we must attend to its specifications. Chassis Compatibility: By having a heatsink, we need enough space on the chassis to put it. Here it is important to see if it supports such mounting. What to normally be 240 or 360 mm with a minimum thickness of 50 mm being fan + radiator

And the truth is that little more, if anything, to see if our board has lighting headers to connect the fans.

Custom refrigeration

This is already another matter, because we have to completely assemble the system. Regarding the aforementioned for AIOs, we are in exactly the same conditions, although of course, we must attend to the compatibility with other components. There are cold blocks for different GPUs, for example, Nvidia RTX, GTX etc. and one of these insurance systems that we are going to implement also in ours. It will be very important to know if the system in question has blocks compatible with our GPU. For reference models they are almost always available, but for the graphic cards assembled by the brands it is more complicated.

Another important factor will be the choice of the chassis, because not all of them allow the installation of pumping tanks. Similarly, flexible tubes are easier to install and more versatile, but rigid tubes give a spectacular appearance.

Finally we must study the way in which we are going to design the circuit, and there are several ways that can be considered standard:

Cold water pumping:

Personally it is the one that we like the most. The circuit scheme to be used will be Pump -> CPU + GPU Block -> Radiator -> Tank -> Pump. In this way the water reaches the tank as cold as possible after passing through the radiator to prevent it from fogging up if it is transparent and RGB. In addition, it goes through the blocks with higher pressure so its effectiveness will be better.

Hot water pumping:

This system has a Pump -> Radiator -> CPU + GPU Block -> Tank -> Pump loop. The good thing about it is that part of the heat is dissipative in the tank itself, but the bad thing is that when passing through the radiator circuit it loses pressure. Also, the heat will fog up the tank and if they are high temperatures we could be in trouble.

Dual stage system:

In this configuration we introduce a second radiator in the circuit, whatever the chosen configuration. This can be placed between the CPU and GPU blocks, or be consecutive with the first radiator.

Maintenance

These systems require in principle the same maintenance as the other components. Although an important factor is added such as the liquid, which inevitably wears away either AIO or Custom.

In the first case, it is a totally closed system, so in principle it should remain unchanged, but in some systems it may need to be filled after a few years, 1, 2 or 3. We will notice this due to an increase in temperatures in the components to be cooled or noise in the pump.

In custom systems, the fluid must be changed more frequently, 1 or 2 years.

Advantages and disadvantages of liquid cooling systems

To finish, let's see what are the advantages and disadvantages that these cooling systems offer us compared to traditional air sinks.

Advantage:

• More efficient system for cooling components.Oriented to configurations with overclocking capacity, and high-performance components.More tidy and with less space occupied on the board.By having the fans off the board, the components get less dirty.It is possible to cool not only CPU, but also GPU and even hard drives, VRM and RAM if the board is compatible Easy installation for AIOMs Better aesthetics and customization capacity Fully adaptable to user needs

Disadvantages:

• They are more expensive than heatsinks We need a compatible chassis Introducing liquid activates the risk of leaks

Conclusion and guide to best liquid cooling

We believe that we have not left anything behind regarding this matter, since we have seen in depth all the elements that make up the refrigeration systems, as well as their operating fundamentals. We leave you now with our guide to the best liquids that we can find on the market.

Guide to the best heatsinks, fans and liquid cooling for PC

Have you ever used liquid refrigeration? Do you think it's worth it? AIO or Custom?