Nah stock standard I have had 528 out of it I don't know if its cpu or ram limited at the moment I may be able to do 550 or 600 but i need to sort the ram timmings out at the moment it is all set by speed in the bios
About core droop...with my P5B DH the voltage is more than CPU-Z shows, but follows the value set in BIOS well, and doesnt droop any worthwhile amount..not checked the VCore Reg IC output though, only probed the VRMs themselves