Dim external monitor brightness

Specified the period of inactivity before client computer automatically reduces external monitor brightness together with the brightness level when display brightness dimmed.

You can specify the period of inactivity in seconds.

This setting is not supported unless both client computer and external monitor supports Display Data Channel/Command Interface (DDC/CI).

Dim display after:

Registry Hive	HKEY_LOCAL_MACHINE
Registry Path	Software\Policies\Lenovo\PWRMGRV\Global
Value Name	DimExternalDisplayTimer
Value Type	REG_DWORD
Default Value	900
Min Value	900
Max Value	4294967280

Dimmed display brightness:

Registry Hive	HKEY_LOCAL_MACHINE
Registry Path	Software\Policies\Lenovo\PWRMGRV\Global
Value Name	DimExternalDisplayLevel
Value Type	REG_DWORD
Default Value	0
Min Value
Max Value	100