TSG: Pen display goes into power saving mode

Pen displays do this because they are not getting a video signal to display. Since they have nothing to show, they shut down their use of power or simply turn off.

To fix the underlying problem of not getting a signal: TSG: Pen display shows NO SIGNAL message

POWER SAVING does not mean a power problem

This message confuses a lot of people. It does not mean the tablet isn't getting enough power. In fact, the opposite is true: if the tablet is showing you this message, it clearly has enough power to run its screen. The message only means "I have no video signal to show, so I'm turning the screen off to avoid wasting energy."

You may still be able to draw

On many pen displays, power saving only turns off the screen - the pen and the data connection keep working. So even with no video signal, you can often still use the tablet as a screenless pen tablet, drawing while you look at your main monitor. Some brands even advertise this as a feature, and some people deliberately disconnect the video cable to use their pen display this way. Not every display supports it, but many do.