Dual Display not working - Manjaro KDE

Thanks could give it a try. What does power cycle mean?

Basically power off the display & put it back on again whilst connected to the computer. Shouldn’t need to pull the mains plug but this might also help. In my case once the display comes on again, the extra monitor appears in the Display Configuration GUI once I do this. That is with an HDMI display connected via the Mini DisplayPort.

Note also that sometimes when I connect my VGA monitor, the display lights up and works but it is not immediately shown in the GUI; clicking “Identify” brings it back in the dialog(ue) window.

I’m having a similar issue but not exactly the same so I’m not sure if I should start my own thread or not. I have 2 monitors and they were both functioning fine until today. When I power on, the secondary monitor shows up in xrandr and the LED indicator indicates that it’s active (i.e. it is not amber indicating a sleeping display or a displaying receiving no signal, but blue indicating that it functions properly).

However, it flickers on for a brief second and then goes black. I’ve seen this before and a simply power cycle of using the on/off switch on the monitor worked, but it doesn’t resolve the issue anymore. Here is my xrandr

Screen 0: minimum 320 x 200, current 4480 x 1440, maximum 16384 x 16384
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080     60.00*+  59.96    50.00    59.94    59.99    59.93  
   1920x1200     59.95  
   1920x1080i    60.00    50.00    59.94  
   1600x1200     65.00    60.00  
   1680x1050     59.95    59.88  
   1400x1050     74.76    59.98  
   1600x900      59.95    59.82  
   1280x1024     75.02    60.02  
   1440x900      59.90  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1440x810      59.97  
   1368x768      59.88    59.85  
   1366x768      59.79  
   1280x800      59.99    59.97    59.81    59.91  
   1152x864      75.00  
   1280x720      60.00    59.99    59.86    60.00    50.00    59.94    59.74  
   1024x768      75.05    60.04    75.03    70.07    60.00  
   960x720       75.00    60.00  
   928x696       75.00    60.05  
   896x672       75.05    60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   832x624       74.55  
   960x540       59.96    59.99    59.63    59.82  
   800x600       75.00    70.00    65.00    60.00    72.19    75.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   720x576       50.00  
   700x525       74.76    59.98  
   800x450       59.95    59.82  
   720x480       60.00    59.94  
   640x512       75.02    60.02  
   700x450       59.96    59.88  
   640x480       60.00    75.00    72.81    75.00    66.67    60.00    59.94  
   720x405       59.51    58.99  
   720x400       70.08  
   684x384       59.88    59.85  
   640x400       59.88    59.98  
   576x432       75.00  
   640x360       59.86    59.83    59.84    59.32  
   512x384       75.03    70.07    60.00  
   512x288       60.00    59.92  
   416x312       74.66  
   480x270       59.63    59.82  
   400x300       72.19    75.12    60.32    56.34  
   432x243       59.92    59.57  
   320x240       72.81    75.00    60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 connected primary 2560x1440+1920+0 (normal left inverted right x axis y axis) 597mm x 336mm
   2560x1440     59.95 +  74.97* 
   1920x1440     75.00    60.00  
   1856x1392     75.00    60.01  
   1792x1344     75.00    60.01  
   2048x1152     59.98    59.90    59.91  
   1920x1200     59.88    59.95  
   1920x1080     59.97    59.96    60.00    50.00    59.94    49.95    59.93  
   1600x1200     75.00    70.00    65.00    60.00  
   1680x1050     59.95    59.88  
   1400x1050     74.76    59.98  
   1600x900      59.99    59.94    59.95    60.00    59.82  
   1280x1024     75.02    60.02  
   1440x900      59.89  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1440x810      60.00    59.97  
   1368x768      59.88    59.85  
   1280x800      59.99    59.97    59.81    59.91  
   1152x864      75.00  
   1280x720      60.00    59.99    59.86    60.00    50.00    59.94    59.74  
   1024x768      75.05    60.04    75.03    70.07    60.00  
   960x720       75.00    60.00  
   928x696       75.00    60.05  
   896x672       75.05    60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   832x624       74.55  
   960x540       59.96    59.99    59.63    59.82  
   800x600       75.00    70.00    65.00    60.00    72.19    75.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   720x576       50.00  
   700x525       74.76    59.98  
   800x450       59.95    59.82  
   720x480       60.00    59.94  
   640x512       75.02    60.02  
   700x450       59.96    59.88  
   640x480       60.00    75.00    72.81    75.00    60.00    59.94  
   720x405       59.51    58.99  
   720x400       70.08  
   684x384       59.88    59.85  
   640x400       59.88    59.98  
   576x432       75.00  
   640x360       59.86    59.83    59.84    59.32  
   512x384       75.03    70.07    60.00  
   512x288       60.00    59.92  
   416x312       74.66  
   480x270       59.63    59.82  
   400x300       72.19    75.12    60.32    56.34  
   432x243       59.92    59.57  
   320x240       72.81    75.00    60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  

The monitor is an old Asus VW246 connected to HDMI and the monitor that works is a new HPZ27

I should maybe start my own thread because I’m using XFCE not KDE

Thanks
Unfortunately Power Cycle did not work
I get a message that the monitor is “scanning for signal” and then “No HDMI Signal from your device”

In your case it could be a failed backlight. Try shining a bright light on the screen; you might see an unlit image.

Running MHWD I notice I have 2 video modesetting boxes checked side by side… Is that normal?

I solved same problem by editing /etc/X11/mhwd.d/nvidia.conf, maybe can help.

Section "ServerLayout"
	Identifier "Layout0"
	Screen 0 "Screen0"
	Inactive "intel"
	InputDevice "Keyboard0" "CoreKeyboard"
	InputDevice "Mouse0" "CorePointer"
EndSection

Section "Files"
EndSection

Section "InputDevice"

	# generated from default
	Identifier "Mouse0"
	Driver "mouse"
	Option "Protocol" "auto"
	Option "Device" "/dev/psaux"
	Option "Emulate3Buttons" "no"
	Option "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"

	# generated from default
	Identifier "Keyboard0"
	Driver "kbd"
EndSection

Section "Monitor"
	Identifier "Monitor0"
	VendorName "Unknown"
	ModelName "Unknown"
	HorizSync 28.0 - 33.0
	VertRefresh 43.0 - 72.0
	Option "DPMS"
EndSection

Section "Device"
	Identifier "Device0"
	Driver "nvidia"
	BusID "PCI:1:0:0"
	VendorName "NVIDIA Corporation"
	Option "NoLogo" "1"
	#Option "metamodes" "nvidia-auto-select +0+0 { ForceFullCompositionPipeline = On }"
EndSection

Section "Screen"
	Identifier "Screen0"
	Device "Device0"
	Monitor "Monitor0"
	DefaultDepth 24
	SubSection "Display"
	Depth 24
	EndSubSection
	Option "AllowEmptyInitialConfiguration" "Yes"
	# Change to your resolution
	Monitor "1920x1080"
EndSection

Section "Device"
	Identifier "intel"
	Driver "modesetting"
	BusID "PCI:0:2:0"
	Option "AccelMethod" "sna"
	Option "DRI" "3"
EndSection

Section "Screen"
	Identifier "intel"
	Device "intel"
EndSection

Section "Extensions"
	Option "Composite" "Enable"
EndSection

Section "InputClass"
	Identifier "Keyboard Defaults"
	MatchIsKeyboard "yes"
	Option "XkbOptions" "terminate:ctrl_alt_bksp"
EndSection

Thanks my file is blank!

Generated by mhwd - Manjaro Hardware Detection

HI. Have just updated to latest 455 drivers but issue remains
For info I have noticed a couple of things and don’t know if they are relevant:

  1. I have 2 videomodestting options installed
  2. I get an error re display link manager not working during the boot cycle

Grateful for your thoughts
R