Latest nVidia 196.75 drivers have fan speed issues and may cause Your graphics card to be permanently damaged.
If You have installed 196.75 uninstall them and install 196.21 WHQL drivers.
Also Blizzard says that 196.75 drivers cause low FPS on Warcraft 3, World of Warcraft and StarCraft 2 Beta.
We're getting reports where users are getting intermittent low FPS after installing these drivers. It seems that it is related to the fan control included in these drivers not working correctly and is causing the video card to overheat on 3D applications. This will affect Warcraft 3, World of Warcraft and StarCraft 2 Beta. Please uninstall the drivers and revert back to the older ones.Blizzard PR