3.4ghz overclock Failure for the second boot

[TerminatorXT]

I overclocked my processor to 3.4ghz (q6600 b3)
it worked the first time and all 4 cores showed up

but the next time when I tried to overclock to 3.6 and failed
I went back down to 3.4 and this time it didn't even show all 4 cores

what went wrong here

 

[jsc]

You may have reached the limit of the CPU. The B3 stepping just isn't as good of an overclocker as the G0 stepping is. I do not see any other limitations in your system. Motherboard, cooling, and power all look good.