Use something to bend the pin straight.
Do you have both power cables in the GFX card?
Have you connected the monitor to the card?
Remove the GFX card and connect to the motherboard.
Have you got the 8pin ATX plugged in near the CPU socket?
Try a clearcMOS
To clearCMOS you need to power off, move the jumper/short the jumper or remove the battery, replace, power ON.