https://bugs.freedesktop.org/show_bug.cgi?id=93471
--- Comment #7 from Malte onlineservices@marwedels.de --- I used the source from Debian, added the source of the mentioned patch and build a new .deb packet. Now xrandr --output HDMI-0 --off reduces power as expected, thanks for pointing to the patch :) But the question remains if it is possible to get the lower power consumption even with two screens (showing the same picture).