I had to crank my BE6-II up to 1.8v with a MSI slocket - the ABIT one I received with my system was DOA. A generic slocket wouldn't allow the bump in voltage to 1.8, so wouldn't boot at 850 (only to 1.75).
Now that I think about it - what IS the "stock" voltage for the C2-566 - 1.5? 1.65?
My system has been running 24/7 now for a few days, I'm going to lower the voltage to 1.75 and see if it's "burned in" enough to be stable. If so, I'll keep going down until I see instability - less voltage is better in the long run! ;-)