What do your temps look like right now? This is a black edition right? If so try increasing only the multiplier until it's not stable, then slowly bump the bus speed, VTT, and north bridge voltage. Also make sure your RAM is at the right speed and timings. Good luck.
What are you using to test with? and RAM isn't black edition or otherwise, it's speed is dependent on the base speed of the board. If you managed to hit 3.75 without changing the multiplier, then more power to you.
and i got it through OCCT for a 15 minute test at 3.75 and i can play borderlands for a couple hours at 3.75 with no issues, but i cant get OCCT to go through its 1hr cycle without BSOD at any settings ive tried when its at anything over 3.45