You just need to look at the tag on it and buy a stepdown transformer that will give you the proper amps and voltage as per the computer. You will probably be fine with a DC transformer running 1a@12 volts, you can go lower, but I would keep the voltage between 7-13V. Be aware as well that most computer fans do not put out tons of air, I would look at the CFM rating and see if it is ideal for your application. I use these for a lot of things, because I repair a lot of computers and end up with a lot of spares. Just as a side note I would not reccomend using pots to regulate this application. A voltage regulator if anything, but they can be a little expensive. You can just use a computer power supply if you have an extra one, just make sure each fan or group of fans has it's ground. Most of the fans I have run between .3 and .7 amps.