Help guys my system isn't booting properly after installing 2 gtx 780's?

Hi guys.

Bought 2 new gtx 780's gigabyte overclocked editions to replace my 2 580's gigabyte overclocked editions . After installing the new cards my computer wouldn't start . A little worried I fiddled around and wondered if its a PSU problem so I put 1 gtx 580 back in and it booted up fine . So I then took the 580 out again and put the 2 x 780's in again and this time my PC started . Problem solved ? No . This time now I am freezing/hanging on the motherboard screen then I'm going to another screen that blinks the _symbol . I will provide screenshots and my system specs to help you guys Analize my problem and hopefully resolve this issue . My guess at this stage is will I have to maybe reformat the whole computer? Maybe try a repair ? I just don't know . Please help?

First screenshot after boot

http://tinypic.com/view.php?pic=2ptwkut&s=5

Second screenshot after motherboard screenshot. Maybe 1 minute . Much longer then when loading to desktop normally

http://tinypic.com/view.php?pic=b6ae77&s=5

Please help .