are you absolutely positive that everything is correctly powered?? (for ex. 6-pin power connector for the 5770 plugged, motherboard 8-pin power connector plugged, etc.)
sometimes you just have to turn the PSU on and off a couple of times to get everything to POST correctly. so that could be it.
sometimes you just have to turn the PSU on and off a couple of times to get everything to POST correctly. so that could be it.