Hi I recently upgraded my pc by adding a new 600w PSU and a AMD R9 280x everything should be compatible but for some reason when I plug the graphics card in it powers on the fans start spinning but it displays a black screen and my monitor displays no signal, There should be a setting in the bios which allows me to use the graphics card instead of the onboard graphics but there isn't .If I unplug the GPU I can still use onboard graphics but if I plug it in I cant . I dont know what to do Ive tried everything literally everything and I don't know what to do because I cant find the setting which allows me to use the card instead of the onboard graphics. SOMEONE PLEASE HELP !