common problem with those boards not playing nice with new cards. I had the same issue with the same board upgrading from 8800gts to AMD 6850. first update your bios, then go into bios and reset to defaults. now take out your 8800 and take out the sli selector card. now install the gtx560 and it should boot. After you can get a display you can put the sli selector back in (i had to re-seat mine a couple times to get all the pcie lanes working) - do the sli selector with the power off obviously. That process worked for me. It should also be noted that some recent cards will not work with this motherboard no matter what you do. If what i told you to do doesnt work, you will need a new motherboard.