I have a ATI 6950 and just recently bought a Dell U2711. When I max out the resolution, the screen has horizontal lines and flickers back and forth. When I turn down the resolution, everything is fine.
Driver's has been updated and the connection is through Displayport, any thing else I should look at to fix this issue?
I would disable the video card, and try through the integrated grafixs just to isolate the issue. If it still does it on the integrated then you might have a bad monitor. I hear dell has a pretty comprehensive warrenty on their high end monitors.