Is that fact that I cant even get 10k in 3dmark06 because of my x2 chip?

Anywho, what voltages have you guys settled on as the safe range for these cards? My card doesnt like to go much over 800/950. Its really hard to find the max though since only 3dmark06 will show any errors and I only have the free version that takes forever to run. Even then it doesnt artifact, it just crashes.