I have the same combination, and I use the win7 utility to bump all cores to 4.2, and was even able to decrease stock voltage (1.15 I think) and it runs very stably. The BIOS auto-overclock bumps bclk and voltage too high for my taste, which burns power and shortens life unnecessarily. Leave all the BIOS settings to AUTO and use the utility for easier overclocking since you can go straight to stress tests. Assuming of course this is the OPs intended question. "Optimal" BIOS settings are very dependent on what you're doing and what your goals are.