And i'm not being arsey about it either, today your post declares that don't know about speedstep, and yet you try overclocking. Every single post about clocking C2D's here mentions read the sticky, it gives every single piece of information you could possibly want including not keeping the voltage at 'auto', and certainly explains what speedstep is. Yes it is remarkably easy to overclock a C2D or a C2Q safely and to a high level, but you've got to follow some basic rules. Read the Sticky and you'll be fine.
To answer your other thread, yes you've probably killed one of the pair of dies, as a Q is really 2 D's one of them might have had a lower tolerance to volatge than the other. You might be lucky and a full bios reset might help, the CPU could have have thrown a fault at the bios that told it to consider it as a Dual, I would hold my breath for it though.