Why is my computer not detecting the graphics card?

1. Make sure the power supply is up to the required wattage for graphics cards.
2. Check all power lines to make sure they are securely plugged in.
3. Unplug and re-plug the graphics card in to the PCI slot.
4. Check the BIOS to make sure the graphics card is set as the primary display.
5. Download the latest drivers for the card.
6. Check for any signs of physical damage.