Hoot (Jul 19, 2001 09:34 p.m.):
When considering the wattage of a rheostat, you must consider the voltage the fan runs at and the current it consumes at that voltage. Based upon most 120s, a 25 ohm 10W should suffice.
Hoot's got a great point and unlike most engineers, I think the same way. None the less, I have had good luck with the 25 ohm rheostats at the Shack and 120 mm fans. I would recommend a voltage regulator over any rheostat though. That's the "Hoot" in me comming out. The only rheostats I have installed in computers are for friends that won't pay a few extra bucks for a voltage regulator circuit.