SPCR

A PWM Controller

The link has gone dead. I used:
http://www.google.com/search?q=DIY+PWM+controller

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 configure it yourself, and with three Scythe Slipstreams regulated down to 200 RPM in idle this finally gives me an inaudible computer. You can find everything you need to set it up on the link below.

https://github.com/szarvas/fanduino

thanks for the detailed write up. i'm looking to build my first fan controller and this helps me get started.

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

Oh wow, that is a great idea. Don't know why I didn't think about using a micro controller to generate the PWM fan speeds. I have a couple of spare ProMicros sitting around here that should probably work for something like that. Maybe someday I'll have some time to look into that. Nice work!