I upgraded my Arduino Nano based solution. I added a custom PCB which is pretty easy to get manufactured these days. And I created a new, nicer looking Windows control software. You can find it all on https://github.com/bebump/coolth https://media.githubusercontent.com/media/bebump/coolth/master/doc...

I just did. I'm using a $3 Arduino Nano replica and some wires to independently control 4 PWM fans and measure their RPM. The fan speeds are controlled dynamically based on CPU and GPU temperatures measured by a PC software sending commands to the Arduino. It requires maybe an afternoon to build and...