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.

It is possible to control the fan speed not by fan PWM, but by PWM of DC input. In that case the fan can be stopped, but RPM data from the fan is messed up. We will start/stop the fan with a MOSFET ...

We recommend making sure your fans are up to a high standard, for both cooler and quieter PC operation. Right now, our testing points to the Noctua NF-A12x25 PWM as the best PC fan today.

This circuit is meant for a 12V fan. I use this controller for the Noctua NF-P12 redux-1700 PWM Fan. This is a dead-simple PWM fan controller that simply lowers the speed of the Noctua NF-P12 ...