Take your memory out of the equation and crank the VCore. Pretty much all you can do. I wouldn't expect you to hit much more than 3.5GHz, especially since you need 1.51875v to be stable at 3.4GHz. Probably just got a dud overclocker compared to some, but there's nothing wrong with a 1GHz overclock.
Your temps are amazing for being over 1.5v though. That's my freaking idle temp @ 1.4v. Stupid concave heat spreader.
EDIT: Oh, and try disabling any spread spectrum settings you may have enabled.