PC fan control

It is an unfortunate and well-known fact that most PCs of the 'IBM and compatible' type make a lot of noise, which is both undesirable (as regards noise in the working environment) and unnecessary (as regards the actual power consumption, which is often quite low). Many fans in PC power supplies are over-rated, noisy, and run at a constant, high, speed. Fortunately, the authors found that such fans can do their protective job just as well at far lower speeds.