First, you will need a much larger PSU, something this:
http://www.newegg.com/Product/Product.asp?Item=N82E16817341003
Then, reinstall the drivers (get the latest drivers from nVidia's web site) and make sure to install them in safe mode when you do.
http://www.newegg.com/Product/Product.asp?Item=N82E16817341003
Then, reinstall the drivers (get the latest drivers from nVidia's web site) and make sure to install them in safe mode when you do.