Lindsey Ellefson is Lifehacker’s Features Editor. She currently covers study and productivity hacks, as well as household and digital decluttering, and oversees the freelancers on the sex and ...

Under normal circumstances, the CPU in your desktop PC generates modest amounts of heat; a smart fan on top of the CPU runs just fast enough to keep it cool. At this speed, you barely hear the fan.

For a CPU, or processor, to maintain a safe operating temperature, it needs a CPU fan. When properly installed, a CPU fan stays in constant contact with the CPU's metal plate so all the heat generated ...