E6600 system unstable after bios update.

Is it normal for a system to be unstable to overclocking after a bios update?
This seems to be the case with mine. I was running stable at 3500, vcore 1.425.
I updated to the 680i bios version p23 and I only last a few seconds at orthos before the system locks.
Is it generally necessary to let the system burn in a bit after bios upgrade? I had the same problem a couple of days ago but attributed it to a beta bios now i am not so sure.
It is not an orthos failure. It is a complete lockup requiring power down to restart.