I have a DELL U2711 Monitor (27" Inches) with a Nvidia GTX 460 video card. The monitor can reach 2560 x 1440 max and the Video card 2560 x 1600 max. But The monitor only reaches 1680x1050. If I use a higher resolution all the screen looks scramble (like the image below).
I have search the Internet and they say the solution was to use a DVI-D (Dual Link DVI) cable. I have been using that cable, but I got a new one just in case and the problem stills the same.
As an extra data for the problem: The DELL Monitor has its own "on screen" Menu, used to choose its settings. In it you can see the info about the resolution. When the resolution is at 1680x1050 or less the Resolution on the Display Menu will show the same. But if I choose the 2560 x 1440 resolution on Windows 7 the Display Menu will show 1280x1440 (as also the image will look as I describe above, please use the link).