Did you make sure you're on the latest GPU drivers? Are you also on the latest BIOS Update for your platform? Speaking of platform, is this a desktop or a laptop? You may need to calibrate your screen(monitor, if desktop) using the buttons located under, on or behind the monitor to bring the screen to it's borders.
I must also ask, if this is an external display, please pass on the make and model and the resolution you're trying to run it off of.