Your card may not be properly seated, make sure your card is seated into the PCIe? slot firmly and completely..You may also have a damaged card..process of elimination can help..Also if this board has a two PCIe setup for games/SLI you may check to see if the power supply is 420+ and you may have to plug a mini molex connector in near the PCIe slots..
Let me know a few more details if I'm off track here..what board? what type graphics card-brand GT-GTS? OS system-etc....
Have or do you have a spare computer to try the card in?