Ok. First off. Pull out your old graphics card. Uninstall all Nvidia stuff off your computer. Put in the new graphics card. Restart your computer. When it says "building driver database" cancel(if you can).

If you can cancel just go into Windows find the Nvidia drivers you downloaded and install them in the default directory. Restart your computer and hopefully it'll work.

If you can't cancel. Go into Windows after it has built the driver database. Uninstall the current drivers. When it asks you(if it does) to restart your computer, click no. Then go to the drivers you downloaded and install them. Restart your computer and hopefully it'll work.

Try downloading different drivers. Example try the Detenator 40 driver. The universal one. Hope this helps.