Check your display cable for loose or bent pins on both ends AND on the connectors they plug into as well. I'd also recommend trying a different display cable. Double check that both ends are firmly and completely seated. If your card has supplementary power from the PSU to the graphics card, make sure that is fully seated.
Try removing and reseating the graphics card. Might also try cleaning the "gold teeth" on the card with isopropyl alcohol. Probably this is a failed card but try these first as it costs you little to nothing to do so.
Also would be helpful to know your full system specs including power supply model (Exact), motherboard, CPU, graphics card and memory specs.