Wish this thread had happened a few days ago. had same issue with my new gpu. upgraded from 7870 to a 290 and was getting the same, everything spinning and starting but no display. Was there for a couple of hours checking drivers, reseating the card in different slots, trying all sorts of combinations with my psu cables in case it was an issue with that. Random chance thought about the mobo drivers etc and flashed the newest bios and all sorted. Upgrades never seem to go to plan, 1 thing always pops up to cause a bit of a headache.