http://www.memtest86.com/ (Gzip) bootable iso burn it to disk...and boot up from start (it does work, i have 64 vista runs on boot start)
as i found out the hard way...memtest86 is a awsome tool to use...unlike anything windows offers in terms of diagnostics..it helped me resolve my cpu issue...(faulty ram was casuing crashing when oc my quad)
but before u use prime and mem test...put everything to default values..and check the memory voltage specs required to run on ur mobo (check manufacturers website for ur mem)...once everything is set to default..and your 100% sure...then run tests overnight for both memory and cpu ul then know if anything is behaving out of the ordinairy.
If it runs fine on default clock it back to 3.2 and play around with the volts...usually 1.35-1.4 v core for ur quad...But..i rekon its ur mobo thats limiting ur oc abilty TBH
____________________________________________________________
Q6600 GO stepping @ 3.2ghz 1.35v/ac freezer 7 (38 idle 57 100% load) (8 x 400 fsb)
4gb Kingston pc 5300 oc 800mhz 5-6-6-18-2T
Asus Rampage Formula
His Radeon 4870 @ 35% fan oc 790/1100 @ 55 idle/71 load
western digital 500gb sata 2 @ 7200rpm
OCZ GameXtreme 600w
19 inch AMW lcd monitor
Vista home premium 64bit