dont mean to sound stupid...but you are downloading these bios files from the XFX website? coz Evga has the exact same bios numbers, but they dont work.
also, are you making sure you are downloading the 680i bios and not the 780i bios?
sorry, have to ask. i didnt have a single problem, i've flashed my board about 3 or 4 times, trying all different bios versions.