Anything over 1080P(1920 x 1080) will require a dual link dvi connection I think.
Right click on your desktop and see if 2560 x 1440 is an option.
To get 2560 x 1440, I think you need a dual link cable which should have come with the monitor, and also a dual link dvi port on your GTX680.
Another option would be to connect via the displayport.
If you want to play with color settings and such, right click on the desktop and go to the Nvidia control panel.