What is liquid cooling and how does it work?

What do you do when you want to cool something down quickly? You blow on it, or if you want to cool it faster, you run it under the tap. This is, in essence, why you use liquid cooling. It’s simply a more efficient means of cooling something. Cars use water and oil as a coolant, ACs use a refrigerant, and bikes – which tend to have smaller engines – use air cooling. But what is the cooling mechanism of desktops and laptops?

Liquid Cooling in PCs

All computers generate heat when they operate, the only thing that varies is the degree of heat that’s generated. That generated heat must be dissipated, and again, one of the most effective ways of dissipating large quantities of heat is using liquid cooling.

Most CPUs generate about 65-100W of heat, and high-end ones will generate about 200W. The most extreme ones can generate more than 200W of heat and need a heavy-duty cooling solution. Air coolers can usually handle a little over 100W of heat, but beyond that they get so large that installing them can become a problem. Beyond 200W, air coolers will become prohibitively large.

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Liquid coolers get around the size problem by moving the radiator elsewhere – usually to the top or front of a case. They consist of the following parts:

1. Pump

2. Radiator

3. Heat sink / water block

4. Coolant

5. Coolant pipes

The water block is a closed system with a copper or aluminium plate on the outside. It attaches to the CPU directly and absorbs heat, which is in turn absorbed by the coolant inside the liquid cooling system. This coolant is continuously circulated by a pump and is carried to the radiators via the coolant pipes (insulated and reinforced rubber pipes, in most cases). The coolant is circulated through radiators, which then dissipate the heat to the surrounding air.

Since these radiators are much larger, multiple cooling fans can be attached to them, allowing them to dissipate more heat. The larger the surface area, the more the fans, the better the cooling.

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You may have seen the terms 120mm, 240mm, and 360mm used to describe liquid coolers. These terms describe the diameter and number of fans that can be attached to the radiators. A 120mm radiator has a single 120mm fan, a 240mm has 2x 120mm fans, and a 360mm radiator has 3x 120mm fans.

Another advantage with liquid cooling is that the liquid takes longer to heat up. At some point, your air cooler and liquid cooler are both going to get saturated and will not be able to dissipate much more heat. Since the liquid coolant can absorb more heat in the short term, your CPU can run faster for longer.

Types of liquid coolers

Here are some common liquid coolers used in computers:

1. All-in-one liquid cooler or AiO

This type is most popular in consumer PCs. An AiO packages all liquid cooling components in one, self-contained system that’s easy to install. These are popular and effective cooling systems and are a great, hassle-free option.

2. Custom-loop liquid cooler

These are liquid coolers where each component, or most of the components, are hand-built or custom-built. These systems are far more complex than AiOs and require more maintenance and monitoring. Enthusiasts and custom PC builders are the ones who go for custom loops.

3. Vapour chamber cooling

A Vapour chamber cooler is very similar to an AiO, with the difference being that the amount of liquid in the system is very small. This liquid is vapourised by the heat, wicked away to the radiator where it cools back into a liquid and then flows to the CPU. This process requires no pump or other moving parts as the process of evaporation and condensation controls heat flow. You’ll find vapour chambers in smartphones and tablets or other devices where higher capacity cooling is required but a liquid cooler can’t fit.

Given how much better liquids are at absorbing heat, liquid coolers are an efficient and cost-effective means of cooling hot components like CPUs. In fact, many modern, high-end gaming PCs, workstations, and even smartphones could not exist without liquid cooling. This technology plays a vital role in keeping the modern world alive.