PWM allows precise fan speed control without noticeable stops, regulating max RPM. Fan sizes and speeds impact noise output, with smaller fans typically being louder. PWM helps increase fan ...

The system allows users to wirelessly control multiple AC appliances like lights and fans through an interactive web interface ...

Of course, the standard way of controlling CPU fans these days is with PWM, so he built a circuit which essentially converts the PWM signal from the motherboard into a phantom thermistor.