Samsung P2450H HDMI Problem

Just unboxed my beautiful Samsung P2450H and it looks superb!

However when using HDMI and setting the resolution to 1920x1080, it doesn't fill the screen.

Theres a black border around the screen and looks incredibly blurry.

When under DVI or VGA it's perfectly fine.

It's plugged into a 5870, and I'm using the latest drives (this is a brand new build.)

Cheers

Just a post to say anyone that gets a similar issue, I followed the steps in this thread and sorted it.

Seems to be a fairly common issue with ATI cards and HDMI

http://forums.overclockers.co.uk/showthread.php?t=18119347

Despite fixing underscan problem; with a samsung 2270 I never obtained
same clarity of text with hdmi input as with dvi; I think this is beacause
sharpness adjustment available in hdmi does not have a setting where it
is disabled; as a result I use DVI input (and hdmi/dvi converter) for regular computer work and hdmi only if I want to watch movies.
[sound unfortunately has to be sent via external cable in dvi mode.]

Cheers, Paul