5 months ago
Last edited at 9:53AM on 11/18/2013
The purpose of most closed loop temperature/fan control systems is to maintain electrical or mechanical devices within their recommended operating temperature range. The 'problem' using computers for example, is that electrical components under normal operation can generate more heat then they are capable of dissipating through passive cooling mechanism alone, so forced air (or sometimes water) cooling is used to lower their temperatures.
The main reason for using a control loop that monitors the temperature and runs the fan at the lowest speed need to provide adequate cooling, is noise. Fans are noisy, so you want to run them as slow as possible in a given situation to provide enough cooling without providing too much added system noise