Water block
A water block is a component used for liquid cooling inside a computer. Like an active heat sink, water blocks are placed on components, like CPUs (central processing units) or GPUs (graphics processing units), to transfer heat away from the computer. Water blocks can be installed on a motherboard using thermal paste and screws.
Water blocks use a metal plate made of a thermal conductor, like copper, to transfer the heat from the CPU or GPU. This plate connects to a chamber with two hoses attached. One hose brings in cold water, while the other removes hot water created by the hardware.
Some GPU manufacturers produce graphics cards with built-in water blocks, allowing you to connect them to your existing water cooling setup when upgrading your computer.