the black and red are hot and cold. the yellow is for fan speed. make sure you look at the Amps the fans are at. Usually they say somthign like 12V .32A this yould mean 320milliamps so you want a 12V adapater that is that or more. If you want more than two fanms you need a power supply that is closer to 1A then you can run three fans I urun 4 Fans of an adapter that is 12V 2A each fan ius rater at .32A

hope this helps

kd_special