Are you using the beta version in-game overlay? That was specifically designed for a 1280 x 1024 display.

The streaming overlay, if you're using it, can be adjusted such that the left side is placed off the screen, as there is no dynamic information that needs to be in the render space for it to update on your streaming software. The size of the overlay can be adjusted in OBS or XSplit or whatever you're using to conform to the limits of your recording resolution.