I'll give ya reply cos no1 else has yet, I have yet to move to a ddr3 system so not yet sure of the way they oc to take fast ddr3 ram but my advice would be:
1. your ram is designed to go that speed so setting your ram voltage to its stock value should be stable.
2. BSOD is a big instability so need to test other components therefore test cpu ONLY using small FFTs in prime95. If that passes the cpu is fine alone, if not look at it's settings. If it passes i'm assumin its in-place large FFTs you have tried and failed at which points to instability between cpu - mobo - ram interfaces, so its watever voltage that is relative to the setting you overclock on the board to use that ram. As i've said i have not looked into it but if it involves increasing the FSB then yeah its possibility NB needs volts untill tests stable with in-place large FFTs.
3. 620 watts may not be a big powersupply for a quad core , big gfx card and hard drives in raid etc, so may be a case of unstable supply of power too. Dont know about enermax, last one i saw was cheap rubbish that came with a case but yours might be an expensive one? one thing u can do is search a web site that has a powersupply calculator like asus have.
hope thats some help and not blind leading the blind lol