A device that draws heat away from a CPU chip and other hot-running chips such as a graphics processor (GPU). The simplest type of cooler is a heat sink, which is a metal cover glued to the chip that provides a larger surface area for heat dissipation. Even more effective is a CPU fan because it forces the hot air away from the chip. It is often used in conjunction with a heat sink. Water-cooled systems and heat pipe coolers provide more esoteric solutions (see heat pipe). Refrigeration systems are also used to cool down the CPU and other hot chips (see below).