The idea behind Panel Self Refresh is a sound one, when displaying static images there is no need for the GPU portion of your processor to be refreshing it at full speed.  If you simply leave the displayed image in the frame buffer you can turn off the GPU and get significant power savings.  It will not help when you are streaming media but if you are reading emails or a pdf file or even browsing pictures, you should see some extension to the life of your battery.  Hardware Secrets describes the technology in their article here.

"Manufacturers are always looking for innovative ways to save battery life on laptops. With the embedded DisplayPort 1.3 interface (eDP 1.3), VESA, the Video Standards Association behind DisplayPort, came up with a new idea, the Panel Self Refresh (PSR). Let’s see how it works."

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Displays