From CPU to radiator. How does liquid cooling work in a computer?

A processor generates heat while it is working, and that heat needs to be transferred away as quickly as possible. In air cooling, the cooler base, heat pipes, heatsink and fan help with this. In a liquid-cooling system, the liquid becomes the main carrier between the processor and the radiator. See how this process works, how a ready-made AIO differs from a custom loop, and when choosing liquid cooling makes sense.

How does liquid cooling work?

Liquid cooling in a computer uses a closed loop of coolant. Heat from the processor passes through the thermal paste to the base of the water block. It is then absorbed by the liquid flowing through microchannels inside the block.

The pump sends the heated liquid to the radiator. There, thermal energy is transferred to thin metal fins, while air flowing through them carries it away from the radiator. The cooled liquid returns to the block and the entire cycle starts again.

Fans are therefore also necessary in liquid cooling. The main difference lies in how energy is transported from the processor to the heatsink or radiator. In an air cooler, this is handled mainly by metal heat pipes, while in a liquid-cooling system it is carried by the circulating liquid.

The effectiveness of the entire system depends on more than just radiator size. The block design, pump operation, fans used and airflow inside the case also matter. A large radiator will not be able to deliver its full potential if the supply of fresh air is restricted.

What components make up liquid cooling?

The design depends on whether you are dealing with a ready-made All-in-One (AIO) system or a self-built system known as a custom loop. The basic components are similar, however.

The water block is mounted directly on the processor and, in custom systems, also on the graphics card. Its metal base absorbs energy from the cooled component and transfers it to the liquid flowing through internal microchannels. Depending on the model, the block may feature lighting, a manufacturer logo or a display, but these visual elements do not change the basic operating principle.

The pump forces the liquid to circulate between the block and the radiator. In designs that allow speed control, its operation can be adjusted to suit the characteristics of the entire system. The pumps used in ENDORFY Navis F-series coolers support speed control via a PWM signal.

The radiator consists of channels through which the liquid flows and thin metal fins that increase the surface area for heat dissipation. Fans mounted on the radiator push air between the fins. The larger the radiator, the more surface area is available for heat exchange, but that does not automatically mean that every larger model will be quieter or more efficient in all conditions.

The coolant transports energy between the block and the radiator. It is most often a prepared mixture containing distilled water and additives that help limit corrosion and the growth of microorganisms. In typical AIO systems, the loop is filled during production and does not require the user to replace or top up the liquid. However, a small number of designs on the market are equipped with a service port.

Hoses or tubes connect the components into a closed loop. In AIO systems, these are usually flexible hoses attached at the factory. A custom loop can use soft tubing or rigid tubes, which require greater precision when routing.

A reservoir, also called a tank, is characteristic mainly of custom-loop systems. It makes filling, bleeding and checking the liquid level easier. It can also be a visible part of the interior design, but its primary role remains supporting operation of the loop. A typical AIO system does not have a separate reservoir intended for user servicing.

What types of liquid cooling are there?

Liquid cooling comes in two basic variants: a ready-made All-in-One system and a custom loop assembled from individually selected parts. Both solutions use a similar operating principle, but they differ in installation, expandability and the amount of maintenance required.

All-in-One cooling

An AIO is a ready-made system filled at the factory. The block, pump, hoses and radiator form a single set, so the user does not have to choose fittings, pour in coolant or bleed the loop.

During installation, you need to attach the block to the processor, place the radiator in the case, and connect the pump and fans to the appropriate headers. In some models, the fans are already mounted on the radiator, which makes the process even shorter.

ENDORFY Navis F-series coolers are built this way. Navis F240 uses a 240 mm radiator and two preinstalled Fluctus 120 PWM fans. Navis F280 has a 280 mm radiator and two Fluctus 140 PWM fans, while Navis F360 combines a 360 mm radiator with three Fluctus 120 PWM fans. You can therefore start choosing a variant by checking which radiator size your case supports.

In the Navis F series, pump speed can also be controlled via PWM. This lets you adjust its operation to the characteristics of your system, just as you adjust fan speed. It is worth choosing the settings based on temperatures and acoustic performance rather than automatically keeping the pump at maximum speed.

Ready-made systems are leak-tested during production. This does not mean that a mechanical device can never fail, but a correctly installed AIO should not be treated as a solution that is inherently likely to flood a computer.

Most AIO systems are designed to cool a single component, usually the processor. A typical model cannot be freely expanded with another water block.

Custom-loop cooling

A custom loop is a system assembled from individually selected parts. It can include a block for the processor and graphics card, while the number and size of radiators can be chosen to suit a specific configuration.

This type of setup gives you more freedom in terms of tube routing, appearance and system expansion, but it requires careful planning of component compatibility. The loop must be assembled, filled, bled and checked before the computer is started.

A loose fitting, incorrectly seated tube or another installation error can cause a leak. That is why the loop is tested before power is supplied to the components.

A custom loop also requires periodic checks and maintenance. The coolant is usually replaced every 12–24 months, but the exact interval depends on the type of liquid, materials used, condition of the loop and the recommendations of the manufacturers of individual components. If the liquid changes colour, deposits appear or the flow noticeably deteriorates, servicing may be needed sooner.

A custom loop is therefore intended mainly for people who deliberately accept the additional work in exchange for full configuration freedom.

AIO or custom loop? The key differences

AIO systems and custom loops use liquid to transfer energy from cooled components to the radiator. That, however, is where the similarities end. From the user’s perspective, the biggest differences concern construction, installation, maintenance and the possibility of later expansion.

For most users interested in liquid cooling, an AIO will be the simpler starting point. A custom loop offers more freedom but requires knowledge, time and regular maintenance. It is therefore not a “better version of an AIO”, but a solution intended for a different type of user.

What are the advantages of liquid cooling?

One of the most important advantages of an AIO is the ability to use a large radiator without placing a bulky heatsink directly on the motherboard. This matters in computers with high-performance processors that run under heavy load for long periods.

Installation of a ready-made set can be made even easier by factory preparation of the radiator. In the ENDORFY Navis F240, Navis F280 and Navis F360, the Fluctus fans are already installed, so you do not need to screw them on separately before installing the system in the case.

An AIO also leaves more free space around the CPU socket. This can make it easier to install tall RAM modules and access some motherboard connectors.

Appearance also matters to some users. In an AIO, the compact block on the processor helps keep the central area of the case tidy. A custom loop offers even greater visual freedom: you can plan the tube routing yourself, choose a reservoir and match the appearance of the coolant to the other components in the system.

What are the disadvantages of liquid cooling?

An AIO has more active components than a typical air cooler – in addition to the fans, it also uses a pump, so there are more potential sources of noise or failure.

You also need to check whether the radiator will fit in the case and whether it will interfere with the motherboard, memory or graphics card. Both its length and its total thickness with fans matter.

An AIO is usually more expensive than a simple air cooler. A custom loop costs even more, and on top of the price of the parts you also need to account for the time required for assembly and later maintenance.

With a custom loop, installation quality is also more important. An incorrectly selected fitting or a poorly seated tube can cause a leak, which is why a leak test is a mandatory stage when building such a system.

Liquid CPU cooling — is it worth it?

Before buying, it is worth considering several factors:

• CPU load — a powerful CPU used for rendering, compiling or other long-running tasks can make better use of the capabilities of a large radiator;
• acoustic performance — radiator size, the fans used and the way the entire system is controlled all matter;
• space in the case — compatibility with the specific radiator size is essential;
• budget — a good air cooler may offer better value in a computer with moderate cooling requirements;
• number of components — an AIO includes a pump and more connections, while an air cooler is structurally simpler;
• appearance and access to components — a compact block on the processor leaves more space around the socket than a large tower heatsink.

An AIO is particularly well suited to computers equipped with high-performance processors that generate a lot of heat during demanding tasks. This includes workstations and configurations used both for gaming and demanding work, such as rendering or other CPU-intensive workloads. Liquid cooling is also worth considering in an enthusiast PC whose user wants to take advantage of the processor’s capabilities when overclocking or using increased power limits.

With processors that have moderate cooling requirements, a good air cooler can also handle sustained loads without difficulty. The length of time the processor is under load therefore does not by itself determine whether an AIO is needed. The most important factors are the amount of heat generated, the characteristics of the specific CPU, the capabilities of the case and the user’s expectations.

A custom loop makes sense mainly when the user wants to cool more than one component, design the appearance of the loop themselves, or treats building and maintaining the system as part of their hobby.

In the ENDORFY range, you can start by choosing the type and size of the cooling solution. Spartan 5 is a compact air cooler, Fera 5 and Fortis 5 use larger tower heatsinks, while the Navis F liquid-cooling series consists of AIO systems with 240, 280 and 360 mm radiators.

Before buying, you need to check the supported CPU socket, the maximum cooler height or the available space for a radiator. Only then should you compare specific models.