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Over the years, Xorg has gotten much better at automatically detecting and configuring monitor resolutions.

For help on manually configuring screen resolutions, please see X/Config/Resolution. For procedures to troubleshoot resolution problems, read on.

How It Works

Computer monitors contain a small binary packet of information called Extended Display Information Data (EDID), which describes the monitor's size, modelines, etc. During startup or when a monitor is hotplugged, the X server queries this data from the monitor and uses it to set a resolution.

Problem: Monitor shows "Out of Range"

This typically happens when the graphics card is trying to use a resolution beyond what the monitor is capable of handling.

First, look and see if a resolution is hardcoded in your xorg.conf. These days this is rarely needed, but if you're using an xorg.conf from an older install or something, it could be set. Try moving aside your xorg.conf and boot without any xorg.conf so it's all auto-detected, or disable the resolution lines.

If booting with an auto-detected configuration doesn't work, then there is a deeper problem. Usually this indicates that the EDID information your monitor is providing is incorrect.

Workaround (for GNOME):

• Start up Ubuntu in Recovery Mode and get a root prompt

• Set GNOME to auto-login, by editing /etc/gdm/gdm.conf and setting AutomaticLoginEnable=true and AutomaticLogin to your preferred user account.

• In your ~/.xprofile add a line to specify a safer resolution:

  # Depending on your video card, your output may be 
  # 'VGA-0', 'VGA0', 'DVI', 'LVDS', etc. instead of 'VGA'
  xrandr --output VGA --mode 1024x768

• You should be able to use System > Preferences > Screen Resolution to fine tune your resolution from here, or see X/Config/Resolution Configuring Resolution for ways to configure resolutions manually.

Workaround (for KDE):

• Start up Ubuntu in Recovery Mode and get a root prompt
• Hardcode the startup resolution in /etc/kde4/kdm/Xsetup (Change VGA to the proper name of your output, like DVI-1, LVDS, or whatever):

  xrandr --output VGA --mode 1024x768

• Modify the mode 1024x768 to your preferred resolution in the above line

There may still be a brief 'out of range' error when the initial wallpaper is shown at full resolution, but then it shifts and login/normal operation follows.

Workaround (for XFCE)

• Please fill this in

Troubleshooting Approach: Review the Xorg.0.log to see how it interprets the EDID information and what resolution it arrived at. Often errors or warnings will indicate where it has gotten confused. For example, "Using fuzzy aspect match for initial modes" indicates it did not find a valid resolution and is extrapolating (evidently incorrectly).

The output from get-edid | parse-edid (from the read-edid package) can be used to examine the EDID more closely.