I OCed my 955 from 16x to 17x and it is running fine. It is a Black Edition so the multiplier isn't locked. Also the 760GM can unlock multipliers. 1st I left the unlock multiplier setting in the BIOS at disabled, then I enabled it but had the same issue.
When I boot into XP or Ubuntu the CnQ feature is disabled. Is that normal? Is there a setting I missed in the BIOS to do both (OC & CnQ)?