I've been having this strange problem with my dual monitor setup. While I've figured out the nightmare of auto-detect not working at all with dual monitors and the inability to use nvidia's configure tool combined with Plasma's monitor option to fix the problem I've switched to nouveau and at least it is consistent now and not messing up my windows and randomly disconnecting.
However, I still have one problem which is getting annoying. DPMS does not work automatically like it should. It says for the monitors the capabilities are off. But then it enables it (but it doesn't - xset shows everything disabled - first two lines are monitors and the last one is a general message saying it's enabled.) $ grep -i dpms /var/log/Xorg.0.log [ 6.087] (II) modeset(0): DPMS capabilities: Off [ 6.156] (II) modeset(0): DPMS capabilities: Off [ 6.174] (==) modeset(0): DPMS enabled [ 6.174] (II) Initializing extension DPMS Now I can run xset dpms 300 450 600 and only then xset shows it as set: $ xset q Keyboard Control: auto repeat: on key click percent: 0 LED mask: 00000002 XKB indicators: 00: Caps Lock: off 01: Num Lock: on 02: Scroll Lock: off 03: Compose: off 04: Kana: off 05: Sleep: off 06: Suspend: off 07: Mute: off 08: Misc: off 09: Mail: off 10: Charging: off 11: Shift Lock: off 12: Group 2: off 13: Mouse Keys: off auto repeat delay: 600 repeat rate: 25 auto repeating keys: 00ffffffdffffbbf fadfffefffedffff 9fffffffffffffff fff7ffffffffffff bell percent: 50 bell pitch: 400 bell duration: 100 Pointer Control: acceleration: 2/1 threshold: 4 Screen Saver: prefer blanking: yes allow exposures: yes timeout: 0 cycle: 600 Colors: default colormap: 0x20 BlackPixel: 0x0 WhitePixel: 0xffffff Font Path: /usr/share/fonts/misc,/usr/share/fonts/75dpi,built-ins DPMS (Display Power Management Signaling): Standby: 300 Suspend: 450 Off: 600 DPMS is Enabled Monitor is On However, while it does blank and turn off the screens it doesn't last. Maybe 10 seconds later the screens turn back on. I can force it with xset to turn the monitors off immediately but same results - after a short time the monitors turn back on. In the X logs there is this: [ 449.529] (WW) EDID timing clock 408.29 exceeds claimed max 75MHz, fixing which makes me wonder if the EDID data is bad on the one monitor (a Samsung monitor.) Does anyone know of a way to test this DPMS? I suppose I could try unplugging the Samsung monitor to see if the problem goes away? One thing that may make a difference is that the Samsung is HDMI and the other monitor (MSI) is DP. However, both of these monitors worked find on my old computer (it was really old, no UEFI support. Can anyone think of next steps? I'm running out of things to try... Dan