Coolbits hack. Google for it. Go in 5MHz increments, I always do core and memory at the same time. Run something like 3dmark and look for artifacts. Then go another 5MHz. When you finally meet artificats, go down one... and try upping core or memory. One or the other. Usually I like memory more than core, but that's just me. (Better to feed the core more than it can handle than have the core starve waiting for information).