Essentially, water cooling systems are divided into two categories: all-in-one (AiO) and custom water cooling systems. With custom water cooling systems, all necessary components are purchased individually and then combined to form a circuit. While custom systems come with more individuality and build-specific cooling, they tend to come with higher prices, too. All-in-one water cooling systems, on the other hand, are often much cheaper and generally have a much simpler installation process. Both custom and AiO water coolers offer RGB and A-RGB options, such as the Liquid Freezer III 240 A-RGB.

A PC water cooler contains a water circuit in which the coolant is moved via a pump (to avoid corrosion and ensure durability, an alcohol-water mixture is often used as a coolant). This pump can be a single component or, as in the case of an AiO water cooler, the pump can be installed directly on the CPU block. The CPU block itself is often made of copper and equipped with fine channels through which the coolant can flow. It is passed through the radiator (also known as a heat exchanger) where it is cooled down by fans optimized for static pressure.