You have Windows 7 installed on your desktop computer.
In the advanced settings of the Screen Resolution Properties screen, you select the Monitor tab to view available screen refresh rates for the current desktop resolution.
In this scenario, an unsupported refresh rate may be shown even though the box is checked to "Hide modes that this monitor cannot display".
Windows determines what modes the display can support based on its parsing of the EDID and not what is returned by the graphics driver. This causes some modes that are not supported by the monitor to be exposed in Windows as an available selection.
Consult the documentation for your display device to determine the supported resolutions and refresh rates.
Install Windows 7 on a PC with an external DVI monitor attached.
Open Control Panel and select the Display applet.
Click on the "Adjust resolution" link.
Click on the "Advanced settings" link.
Select the Monitor tab.
Under the "Screen refresh rate:", an unsupported mode may be listed even though you have a check mark in the box below for "Hide modes that this monitor cannot display".