If your computer is connected to an external monitor and you try to change the brightness level, the Brightness Meter may appear, but the brightness level on the external device does not change. NOTE: Brightness key combinations only affect the display on your portable computer, not monitors or projectors that you attach to your portable computer or docking device. When a Dell� computer is running on battery power, you can conserve power by setting the brightness to the lowest comfortable setting by pressing and the up- or down-arrow key on the keyboard. Setting Display Resolution and Refresh Rate
Using the Display: Dell Latitude D630/D630c User's Guide
