High Quality Content by WIKIPEDIA articles! In electronic systems, a heat sink is a passive heat exchanger component that cools a device by dissipating heat into the surrounding air. In computers, heat sinks are used to cool central processing units or graphics processors. Heat sinks are used with high-power semiconductor devices such as power transistors and optoelectronic devices such as lasers and light emitting diodes (LEDs), wherever the heat dissipation ability of the basic device package is insufficient to control its temperature.