I had celeron 400@450 and have just upgraded to a celeron 566@707 , with no probs at all but my goal is 850. I'm running a Abit BH6 M/board with socket converter plus the latest bios update bh6_ss.bin. These are all the same nothing has changed there so why when running my 400 was the core voltage able to adjust from 1.30 to 2.30 but when i install the 566 it only adjusts from 1.30 to 1.70, which it seems where the problem lies as most people i have spoken to run them at 1.80 to 1.90 to gain stability. Can anyone please help because at 850 my system is very unstable.