Nvidia 6600gt or Monitor , problem ?

I will get to point quickly.

I have a viewsonic vx922. Witch clearly indicates
the refresh rate is the following :
Resolution:
1280 x 1024 @ 60, 75 Hz
1024 x 768 @ 60, 70, 75, 85 Hz
800 x 600 @ 56, 60 72, 75, 85 Hz
640 x 480 @ 60, 67, 72, 75, 85 Hz
720 x 400 @ 70 Hz
HDTV: 1280 x 720 @ 60 Hz (720p)

And then I also have a nvidia 6600gt witch as you know can be used with 60-70-72-75. Well then, I have all the updates up to date, screen and cables set and connected correctly to the computer but still.

When I set my nvidia screen setting to anything above 60hz: for example 70hz it makes the screen go black, and the green light on the monitor to flash.
I have tryed on Resolution 1280 x 1024 75hz and I have tried 800 x 600 72,75hz...

Still the same result.

And if its normal tell me if its not try to figure out or ask me questions to know what I should buy. Monitor or grafic card ?
Cause I need more then 66fps in game and I cant stand the screen get tired to fast.

Thanks

It's normal to get a fixed refresh rate at perticular resolution and as 6600GT is quiet outdated card it wont support high refresh rate at high resolutions .There is no problem with your monitor but you need to get a new graphic card to get higher refresh rates.