Ok guys,I honestly have no idea what has happened.
I'm running a HDMI from my GTX 670 graphics card to my 40inch 1080p monitor.
However when I set my resolution to 1080p, it's too large for the screen and goes pixlated...
1680x1050 seemes to fit perfectly though.. I double check the 40" screen is 1080p.
Look at the nVidia Control Panel and see if there is something called Overscan / Underscan. I know it exists for Radeon cards. It purpose is to fix the exact issue you are describing when the native resolution desktop is larger than the screen.