go to the monitor properties page and make sure "hide modes that monitor can't display is checked" you'll see what you can run.
Then go to your vid properties and lock in that rate also in the adapter page. 85 should be right I think. You can wreck your monitor(although it will probably go dark before that)if you go to high.
you should always go as high as the monitor and the video card support. using reforce will allow you to use higher rates that fit within the inf's. higher the refresh the cripser the image and less fatiguing to the eye/subconscious, seriously.