Does the display itself have any over/underscan options in the internal set up if it has one? Worth checking, maybe it is doing something dumb internally. Otherwise basically I agree with if you can use any other connection type than hdmi, unless hdmi is the only digital connection on the display I wouldn't use it.
On my Samsung TV, unless you select one of the manual options, it does exactly what you are saying. On my Panasonic one... Good luck with that. No amount of tinkery works. Use the VGA in and everything is hunky dory...
Updating chipset drivers didn't work but luckily I found an old vga cable which I connected to my graphics card with a vga to dvi adaptor. The image fills the screen properly but isn't as sharp as with the HDMI cable. It'll do for now though because at least I can see everything. There's no option on my monitor for underscan/overscan though. Thanks for all your suggestions
It might all be fixed if you can use a DVI cable. (Or get a new monitor, your card is extremely happy at 1080p )
Yeah I think I'll get a dvi cable tomorrow, I've actually got a 23inch 1080p monitor but I don't have it with me at the moment unfortunately. Thanks for taking all the time to help