Wikipedia
Computer cooling is required to remove the waste heat produced by computer components, to keep components within permissible operating temperature limits Components that are susceptible to temporary malfunction or permanent failure if overheated include integrated circuits such as central processing units (CPUs), chipsets, graphics cards, and hard disk drives Components are often designed to generate as little heat as possible, and computers and operating systems may be designed to reduce power consumption and consequent heating according to workload, but more heat may still be produced than can be removed without attention to cooling Use of heatsinks cooled by airflow reduces the temperature rise produced by a given amount of heat
Computer_cooling#Heat-sinks - Wikipedia, the free encyclopedia