This plagued me too long
, so thought I'd document the solution for others.
Problem: Using HDTV and ATI video card you have a black border around desktop (it doesn't fill screen).
Solution: This is caused by an incorrect value for your overscan. To correctly set it see this article:
http://support.amd.com/us/kbarticles/Pages/GPU72ResDoesNotMatchDesktop.aspx
Yea, now my 50" tv is really 50 and not 45!
Cheers,
Chunkydark
