When I add below config in xorg.conf: Section "ServerFlags" Option "StandbyTime" "1" EndSection DPMS will work after 1 minutes. But after I disable DPMS in xorg.conf by adding below line in "Monitor" section: Option "dpms" "off" Monitor still be black after 1 minuter. So DPMS still work.
I think this is actually a server bug.
Fixed by xserver commit 544cd9e7b50cd9905afc52404de1a5a2bcff91b5. Closing.
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