1280x1024@60 Hz
1152x864@75 Hz <-- Using this now
1024x768@85 Hz
800x600@85 Hz
What model is your monitor?
And by which Manufacturer?
My current monitor does :-
1600x1200@72Hz <-- Current Resolution
1280x1024@85Hz
1024x768@100Hz
800x600@120Hz
640x480@150Hz