have you tried them at lower volts? what temps are you getting?
(currently running mine at 4.8 on 1.37 volt (dropped from a higher clock as i had no need for the extra speed)
i only prime95d it for 6 hours, but meh, i need my computer, i can't live without it for a full 24 hour prime 95
edit: check http://www.overclock.net/intel-gener...uide-p67a.html for help with turbo and volts and all sorts of other complicated crap (stuff like the bios/mobo auto volting itself to a certain point etc)