Sleep power feature is not available after driver install on multi-display adapter systems.


Symptoms


Sleep power feature is not available after driver install on multi-display adapter systems.

Cause


Microsoft’s default VGA/Standard VGA Video Driver which is found in the file VGAPNP.SYS is installed on all display adapters that have not been updated with a third party specific display driver. The Standard VGA Driver does not support any sleep modes and will prevent the system from enabling the sleep power features. Therefore even if one remaining display adapter is using the Standard VGA Driver it is enough to prevent the sleep features from being enabled in Windows. The Standard VGA Driver requires a restart to be unloaded. Standard VGA Driver will prevent the sleep power feature until the system is restarted after all of the display adapters have been updated. Typically the system will prompt the user for a restart when needed except in some cases such as when the display adapter has no monitor connected in a multiple display adapter system.

Resolution


Update the display driver for every video adapter on the computer and restart after each and every display driver install. The sleep power features will be enabled following the restart after the last display driver has been updated.

More Information


How to use the Powercfg.exe tool to determine if this issue is the cause of your sleep power feature being disabled

You can use the Powercfg.exe tool to help you determine the reason(s) the computer’s sleep power features are not available.  The Powercfg.exe tool is installed with Windows 7. 

To set the active power plan by using the Powercfg.exe tool, follow these steps:

1.           Click Start  , click All Programs, and then click Accessories.

2.           Right-click Command Prompt, and then click Run as Administrator. If you are prompted for an administrator password or for confirmation, type your password, or click Continue.

3.           Type the following command, and then press ENTER:

Powercfg -availablesleepstates

4.         You have this issue described in this article if you see “The VGAPNP.SYS display driver does not support standby.  Please consult your hardware vendor for an updated display driver.”

 

For more information about the Powercfg.exe tool, visit the following Microsoft Web page:

 http://technet2.microsoft.com/WindowsVista/en/library/1d58b934-f56a-4796-b2df-7be2eb9c03bc1033.mspx?mfr=true