I don't intend on overclocking.
I'm not trying to be a d1ck, but if you were not planning to OC WHY did you get the Rampage III?????
As far as PSU goes, a QUALITY 650W XFX, Seasonic, Antec, Corsair,etc will be fine. HOWEVER, if you plan to CrossFire or overclock later get a quality 750-800W.