*update*
So I OC'd the Q6600 to 2.80GHz (stock/air cooled) and it's significantly better with less stuttering. I tried 3GHz but it didn't even POST (thankfully BIOS automatically put it back to what it was). Guide said to leave voltage on Auto... which brings me to this...
My concern now is heat. I don't know what the temp is in-game (switching back and forth results in crash), but HWMonitor shows a few cores hitting 98C when I go to encode a video. Yikes. I think previously it went up to 90C. I know that's still high, but this can't be good. Do you think lowering the voltage to an actual number will help, given that it was 90C with load even before OC'ing?