I just changed some fan connectors on my Asus P8P67 Pro yesterday and here's what I can tell you. The "power fan" connector is just another 3-pin connector that will accept any 3-pin fan. However, BEWARE: that fan cannot be controlled from Asus AI Suite II (or BIOS, but that I'm not sure aboot) and therefore runs on high RPM and annoys you with noise (that's why I took my 140mm top fan and switched it to a regular "chassis fan" 3-pin connector).
Your PSU fan will power itself from the PSU, no need for additional connectors. That said, do you by chance find your TX750 (I assume it's TX750, correct me if I'm wrong) too loud on idle?