Currently I own 1 120 mm SP white led fan from corsair, I can get 2 AF fans for $16 along with the new Phanteks Enthoo Pro M I'm getting. I've read that since it has no drive bays, I could use AF for intake. But with that remaining fan, could I use it for the rear output? I know it's a silly question. Or should I invest the money in another SP fan with pair up in the front and use the AF at the top?