i had my e8400 @ 4.32ghz @1.38v(actual, set 1.4v in bios) on my pencil modded 780i(fixed vdroop). my q6600 ran at 3.6ghz @ 1.5v and 3.9ghz @ 1.56v

the NB was set to 1.5v, ram was set to 2.3v(your's may be lower, and probably should be). everything else is set to auto.