http://us.download.nvidia.com/Windows/260.99/260.99_Win7_WinVista_Desktop_Release_Notes.pdf
This could be it?? Not sure
Special Instructional Notes
Help for Resizing Your HDTV Desktop
After resizing the HDTV desktop, the new custom resolution created is now added to the
list of available resolutions for that display, and also added to the resolution list within
the game or application.
In Release 190 and later drivers, the method for resizing the HDTV desktop has changed
to provide better image quality when applying underscan. This method results in a new
custom resolution being created which needs to be selected from games or applications to
apply the resizing.
In the example displayed in the following screen shot, the underscan has created a new
resolution (1216x682). Although this resolution looks different, it is still in HD format.
Remember to select this resolution in your game or other application in order to take
advantage of it.
Note: