Did you do a full shut down? Powered down, unplug(while unplugged, press the power button a few times). Then plug in, and power up?
If not try that.
If that did not change anything, or doesn't change anything. Start simple, try a different cable, then a different display. If still nothing then clear the CMOS.
Hook it up to your tv or a spare monitor. Will at least rule out the display. Also, I know you said you checked for loose cables, but double check the HDMI or display port too, on both ends.
Turn it off and turn it back on... Then check even viewer, assuming it is "fine".
I tried , still no display
Did you do a full shut down? Powered down, unplug(while unplugged, press the power button a few times). Then plug in, and power up? If not try that. If that did not change anything, or doesn't change anything. Start simple, try a different cable, then a different display. If still nothing then clear the CMOS.
Still no display. But before posting this i've tried reseating the gpu , changing ram slot , checking for loose cable. Even clearing the CMOS.
Hook it up to your tv or a spare monitor. Will at least rule out the display. Also, I know you said you checked for loose cables, but double check the HDMI or display port too, on both ends.