Graphic card failure

I am having problems with my graphic card I get a message saying "Display driver has stopped responding and has recovered" my Graphic card is a Nvidia GeForce 9800 GT OC, I am running Windows 7 64 bit and was told I have to install the windows 7 64 bit drivers, I downloaded them, but when I try to uninstall the only driver and i reset my pc windows 7 automatically installs the auto drivers. I tried going into systems-advanced system settings-hardware-device installation settings and clicked No, let me choose what to do and Never install driver software from windows updates, and disconnected from the internet, but when I reset it still updates. I called tech support and they told me that I may have to delete all the Nvidia drivers off windows 7 she also said it could be a hardware use with the graphic card, ram, or proccessor, or not enough power, but my power supply is 800 watts. Does any one know what I should do?

 

try running driver sweeper,
http://majorgeeks.com/Driver_Sweeper_d6171.html
use it to remove all nvidia graphics drivers. Reboot, and install the new ones.
http://www.nvidia.com/object/win7-winvista-64bit-258.96-whql-driver.html