Zalastair Clark said:
Your power supply isnt big enough if you have any overclocking done. The 2 graphics cards can use up to 400 watts overclocked. Leaving you with only 250 for mobo hard drives fans processor and ram
They are only 170w cards and as I have had SLi'd 170w cards running on a 620w PSU I would have to disagree with you on that.