Need to run a lot of fans off of one speed controlled connecter? Or maybe one very power hungry fan you are afraid to connect to you motherboard? This mod is for you. All you need is some connecters, which you probably already have, a MOSFET, and a resister, and a soldering iron.
I used a Fairchild N-Channel MOSFET I got from mouser (P/N 512-FDP3682). I chose it to control some fans for a friend’s computer because it had a very low on resistance and very high amperage handling capabilities, 32Amps! This should be more than enough for a whole lot of average case fans or a few very high powered fans.