This project can be used to spoof the speedometer signal that fan controllers (such as BIOS) expect. Nowadays it often happens that fans do not switch off completely, even though the temperature is low enough. This project can help to implement a controller that switches off the fan when it is not needed. Otherwise, the BIOS or the fan controller would realise that it is no longer receiving a speed signal and then try to speed up the fan.
Credits: https://wolles-elektronikkiste.de/timer-und-pwm-teil-2-16-bit-timer1