Technically, it's a "Thermistor," not a thermostat, but it is still a neat mod, doesn't take up much more space than just the fan, it's cheap, and anyone with the slightest bit of soldering skills should be able to complete this modification. Because it is controlled by the temperature sensor, it isn't running all the time at full speed, and there is no need to manually adjust your fan speed like other mods on this site mention. Exact instructions came from here, and unfortunately, they will not permit me to post the diagram here: http://www.heatsink-guide.com/content.php?content=control.shtml Since the Radio Shack thermistor is NLA, I ordered a lot of thermistors off of eBay. Any 10K @ 72 deg F (22 deg C) NTC (negative temperature coefficient) thermistors should work just fine. Either the glass rod or round. It needs to be run off of the 12V circut on the WRT. Im sure most of you know where to find that on your router.