Also known as liquid submersion cooling, it is the practice of submerging computer components (or full servers) in a thermally, but not electrically, conductive liquid (dielectric coolant). Liquid submersion is a routine method of cooling large power distribution components such as transformers. Still rarely used for the cooling of IT Hardware, this method is slowly becoming popular with innovative datacenters the world over. IT Hardware or servers cooled in this manner don’t require fans and the heat exchange between the warm coolant and cool water circuit usually occurs through a heat exchanger (i.e. heater core or radiator).
The liquid used must have sufficiently low electrical conductivity not to interfere with the normal operation of the computer. If the liquid is somewhat electrically conductive, it may be necessary to insulate certain parts of components susceptible to electromagnetic interference, such as the CPU. For these reasons, it is preferred that the liquid be dielectric.