Do you have your mem voltage & timing set to manufactures specs? I have an ASUS board but see if your bios has similar features which can be disabled for overclocking. Also, make sure your multiplier is properly set. Obtaining stability may also require raising your NB, SB, and other voltages. Have you tried Linked/Synced mode, not as good as being unlinked but might be a good place to start.
I'll be honest with you, overclocking is kind of a personal thing between you and your board........Trial and error only you can resolve.
Spread Spectrum Control: All Disabled
CPU Internal Thermal Control: Disabled
Limit CPUID MaxVal=Disabled
CPU C State Capability=Disabled
Execute Disable Bit=Disabled
Enhanced Intel SpeedStep Technology=Disabled