The first time the display manager runs in a new graphical environment, either a newly installed system or one with new graphics hardware, the X server attempts to create a default resolution of 800x600 with 256 colors using a compatible accelerated graphics driver. If an accelerated driver is not available, the server will attempt the default resolution (800x600 with 256 colors) using the SCO VESA (Video Electronics Standards Association) driver. This driver is compatible with many contemporary graphics adapters. If your adapter cannot be configured with the VESA driver, the X server defaults to standard IBM VGA mode. After the initial login, you can continue to use the default, or run the Video Configuration Manager to select another resolution supported by your hardware.
Some resolutions only work if you have enough video adapter memory. Make sure you have at least the minimum DRAM or VRAM to support the desired number of colors at the specified resolution:
Memory requirements for color support at specified resolutions
|(4 bits)||(8 bits)||(15/16 bits)||(24 bits)||(32 bits)|
Refer to your video adapter documentation for additional information on memory requirements.
If you select resolutions of 1024x768 or higher, you may need to determine if your monitor works in interlaced or non-interlaced mode at these resolutions. Consult your monitor's documentation regarding supported resolutions.