With the Nvidia Control Panel, adjust your scaling options to remove that border. Make sure Windows is set to the native resolution of the display first, though.
This worked for another guy:
go to CCC>graphics>desktop and displays>please select a display>click on black triangle for LCD (not HDTV)>configure>attributes>scale image to full panel size
You could also try going to Nvidia control panel and seting the resolution to the native resolution if it changed with the cable for whatever wierd reason.
With the Nvidia Control Panel, adjust your scaling options to remove that border. Make sure Windows is set to the native resolution of the display first, though.