A water-cooled PC works similar to the cooling system of a car. It uses the basic principle in thermodynamics: heat transfers from a warmer object to a cooler object. A water pump moves water through water blocks to the different components of the PC that produce heat. The water absorbs heat from the GPU, the CPU block and other high-temperature chipsets, cooling these components in the process.
Water has better thermal conductivity and heat capacity compared to air and other liquids, which means it is the ideal for holding and transferring heat. Because most electronic components are damaged when they have direct contact with water, liquid-cooled PCs use water blocks, such as aluminum or copper, over the chipset. These are filled with hollow channels and tubes that move to the radiator, which dispels heat into the air through a fan, allowing the water to cool as it passes multiple channels inside the computer. Most water-cooled PCs also have a reservoir that stores extra water for easier addition of a coolant.
While tap water can be used to as a coolant, distilled water is recommended, as the former usually contains contaminants that may clog the channels in the radiator or water blocks. Liquid colorants can be added to make the water-cooling system visually appealing, as well as anti-corrosion and antimicrobial ingredients that claim to lengthen the lifespan of the cooling system.