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Janghou
Asked: 2019-08-22 12:11:55 +0800 CST

Monitors do not turn off (enter powersave mode) after screen blanking

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Ubuntu 1904, both X and Wayland. AMD 2400G, ASUS motherboard with 3 screens: HDMI,VGA,DVI.

When I leave my computer, it will blank the screen after the timeout, then my 3 monitors will fall asleep, but they will wakeup after 10 seconds or so, and never enter power save mode again. They will keep showing the lock screen.

So it is a costly affair, burning 100 Watts, and shortening lifespan of my screens.

Also when I turn off my screens manually:

xset dpms force off

They turn off, and wake up after 10 seconds.

Could be this bug 1292041. But I doubt because it's is also happening when powering off the screens with xset.

How do I get my screens to enter powersave mode?

power-management multiple-monitors lock-screen screensaver

2 Answers

  1. WORKAROUND

    Change the setting of your monitor from input select: auto to a fixed input, e.g. hdmi.

    Here, with a AOC Q3279VWFD8 (WQHD):

    OSD -> extra -> input select -> hdmi (was auto)

    That fixed my problem, also that setting prevented my other monitors from entering powersave mode (turning off). It seems a monitor can poll the graphic card through HDMI (CEC?), preventing powersave mode. Probably cable type plays a role as well.

    Still I consider this a bug, IMHO powersave mode should work with default settings of monitors.

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  2. Only thing that helped was turning off the automatic screen lock. even if the monitor was set to auto=off , and hdmi selected, the problem still happened after manually locking the screen, it came back on in about 5 seconds by itself and left all the connected monitors on too.

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