Some Nerdy Stuff

October 25, 2009

Troubleshooting Windows 7 desktop resolutions.

Filed under: Uncategorized — aaronls @ 8:22 am

After upgrading to Windows 7, users may experience problems where Windows 7 tries to use a resolution or refresh rate that is not supported by their monitor, which in most cases will just present a blank screen with a monitor message indicating something along the lines of “Mode not supported”.  For example, when connecting a Samsung 50″ HL50A650 DLP television via a VGA connection, only a few resolutions are supported and for those most only support a 60Hz refresh rate.  Windows 7 may incorrectly detect the monitor and default to a resolution or refresh rate not supported (users have reported a incorrect default of 59Hz to be a problem).  Since the user has only a blank screen, it is impossible to change settings to troubleshoot the issue.

1) First, the user needs to either boot into a VGA Safe Mode (via the Enable VGA Mode option accessed by pressing F8 during bootup) and hope the defaulted resolution is supported by the TV/Monitor, or temporarily connect a monitor that Windows detects correctly.

2) Now the user should download and install the latest drivers for their graphics card.  Then connect the problem TV/monitor, turn it on, and reboot the computer.  If the TV/monitor is not connected and turned on before booting up the computer, Windows may not be able to detect it correctly.

3) If step #2 did not solve the issue, the next step is to disable the Extended Display Identification Data (EDID), which should prevent the graphics driver from trying to guess the monitor’s capabilities, since it is clearly doing a poor job of guessing.  The following is how to do so using the Catalyst Control Center for thus running that driver suite with an ATI graphics card.  If anyone with this issue on an NVIDIA card is able to provide the equivalent steps, please do so in the comments.

For ATI Catalyst Control Center:

3.a) Right click an empty area on the desktop, and choose Catalyst Control Center.
3.b) In the top left Graphics menu, choose Desktops & Displays.
3.c) In the bottom left where a monitor icon is shown, click the black triangle and in the menu that is displayed click Configure…
3.d) Clear the checkbox for Use Extended Display Identification Data (EDID) or driver defaults.  This will prevent Windows from attempting to change resolution and refresh rate settings when it incorrectly detects the monitor during bootup.
3.e) Now set the Maximum resolution setting to what the monitor’s specifications indicate is it’s maximum, and also set the maximum refresh rate.  In the case of the Samsung 50″ HL50A650 DLP, set the Maximum refresh rate to 60Hz and Maximum resolution to 1920×1080.  Click Apply.
3.f) From the Graphics menu, select Desktop Properties.

3.g) Set the Desktop area and Refresh rate to a resolution and refresh rate known to be supported by the TV/monitor.  The Force… menu can be used to force settings in the case that the ATI driver doesn’t think your monitor supports those settings.  Be absolutely sure that the TV/monitor supports these settings, as there is a chance that it could be damaged by using incorrect settings.
3.h) Click Apply to save the settings, reconnect the TV/monitor you intend to use if you had swapped it out for troubleshooting, and reboot.


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