If.. Power is correctly supplied to the card, drivers were removed and installed correctly, and the card is not overheating. I seriously suggest replacing the card. Get an RMA, and get a new card sent out to you. Some cards are just bunk on arrival its not uncommon.
If you have not tried already. Install a program called SpeedFan. This will monitor the temps of your GPU, and CPU. It is possible that the card itself is fine, and the issue is with the CPU and RAM. The odd thing tho is that if it was a power issue or an overheating issue, you would most likely be seeing the video card driver crash often, or your machine just mysteriously shutting down. Once again leading to the idea of a bunk card.
(No malware on SpeedFan. Also read everything when installing free software from the internet. 99% of it will install useless crap if you don't unchecked those boxes in the instal. It helps to pay attention to what you are installing on your computer.) Too much useless crap from the internet can also start to cause mystery issues when piled up too high.
