make sure you're on the latest version of the bios then try raising the cpu volatage to 1.4v. its safe as those chips tend to run cool.
If that doesnt work back down the cpu multiplier a few or more and try again.
If at any point it works be sure to stress test the cpu to be sure its stable.
if it passes the multiplier by 1 and retest. and keep repeating to find your max cpu speed.