Dual monitor setup only one monitor ever detected

Support Graphics & Display
,
1

Hi,
I have a dual monitor setup that previously worked fine, but stopped working after I disconnected one monitor to use for something else and then reconnected. The monitors are both connected via Displayport. When I have both monitors connected only one is detected and working. As soon as I disconnect the working monitor the one that previously was not working is detected and works fine. On the login screen both monitors work but as soon as I log in one switched of and displays “No DP signal detected”

With both monitor connected
inxi -Fzxu

  Kernel: 5.15.41-1-MANJARO arch: x86_64 bits: 64 compiler: gcc v: 12.1.0
    Desktop: KDE Plasma v: 5.24.5 Distro: Manjaro Linux base: Arch Linux
Machine:
  Type: Desktop System: Dell product: OptiPlex 9020 v: 00
    serial: <superuser required>
  Mobo: Dell model: 0PC5F7 v: A02 serial: <superuser required> UEFI: Dell
    v: A24 date: 10/24/2018
Battery:
  Device-1: hidpp_battery_0
    model: Logitech MX Vertical Advanced Ergonomic Mouse
    charge: 55% (should be ignored) status: discharging
CPU:
  Info: quad core model: Intel Core i7-4770 bits: 64 type: MT MCP
    arch: Haswell rev: 3 cache: L1: 256 KiB L2: 1024 KiB L3: 8 MiB
  Speed (MHz): avg: 1245 high: 2590 min/max: 800/3900 cores: 1: 2590 2: 798
    3: 798 4: 798 5: 2225 6: 799 7: 799 8: 1153 bogomips: 54299
  Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
Graphics:
  Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics
    vendor: Dell driver: i915 v: kernel bus-ID: 00:02.0
  Display: x11 server: X.Org v: 21.1.3 driver: X: loaded: modesetting
    gpu: i915 resolution: 1: N/A 2: 2560x1440~60Hz
  OpenGL: renderer: Mesa Intel HD Graphics 4600 (HSW GT2)
    v: 4.6 Mesa 22.0.4 direct render: Yes
Audio:
  Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor HD Audio
    vendor: Dell driver: snd_hda_intel v: kernel bus-ID: 00:03.0
  Device-2: Intel 8 Series/C220 Series High Definition Audio vendor: Dell
    driver: snd_hda_intel v: kernel bus-ID: 00:1b.0
  Device-3: Plantronics Plantronics Blackwire 325.1 type: USB
    driver: plantronics,snd-usb-audio,usbhid bus-ID: 3-12:5
  Sound Server-1: ALSA v: k5.15.41-1-MANJARO running: yes
  Sound Server-2: JACK v: 1.9.21 running: no
  Sound Server-3: PulseAudio v: 15.0 running: yes
  Sound Server-4: PipeWire v: 0.3.51 running: yes
Network:
  Device-1: Intel Ethernet I217-LM vendor: Dell driver: e1000e v: kernel
    port: f080 bus-ID: 00:19.0
  IF: eno1 state: up speed: 1000 Mbps duplex: full mac: <filter>
  Device-2: Ralink RT5370 Wireless Adapter type: USB driver: rt2800usb
    bus-ID: 3-7:4
  IF: wlp0s20u7 state: up mac: <filter>
Drives:
  Local Storage: total: 1.81 TiB used: 316.7 GiB (17.1%)
  ID-1: /dev/sda vendor: Intel model: SSDSC2BW480A4 size: 447.13 GiB
  ID-2: /dev/sdb vendor: Samsung model: SSD 860 PRO 512GB size: 476.94 GiB
  ID-3: /dev/sdc vendor: Western Digital model: WD1003FZEX-00K3CA0
    size: 931.51 GiB
Partition:
  ID-1: / size: 451.27 GiB used: 42.19 GiB (9.3%) fs: ext4 dev: /dev/sdb2
    uuid: b762e455-c5b1-4ddb-9df6-c76e33b2c79d
  ID-2: /boot/efi size: 299.4 MiB used: 292 KiB (0.1%) fs: vfat
    dev: /dev/sdb1 uuid: 50C8-29A4
Swap:
  ID-1: swap-1 type: partition size: 17.09 GiB used: 0 KiB (0.0%)
    dev: /dev/sdb3 uuid: 4bac82a9-c287-42b5-b706-9bcd184a826b
Sensors:
  System Temperatures: cpu: 29.8 C mobo: 27.8 C
  Fan Speeds (RPM): N/A
Info:
  Processes: 227 Uptime: 17m Memory: 15.54 GiB used: 2.27 GiB (14.6%)
  Init: systemd Compilers: gcc: 12.1.0 clang: 13.0.1 Packages: 1242
  Shell: fish v: 3.4.1 inxi: 3.3.16

and xrandr output:

Screen 0: minimum 320 x 200, current 2560 x 1440, maximum 16384 x 16384
VGA-1 disconnected (normal left inverted right x axis y axis)
DP-1 connected (normal left inverted right x axis y axis)
   2560x1440     59.95 +
   2048x1080     60.00    24.00  
   1920x1080     60.00    50.00    59.94  
   1920x1080i    60.00    50.00    59.94  
   1600x1200     60.00  
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-2-8 connected primary 2560x1440+0+0 (normal left inverted right x axis y axis) 597mm x 336mm
   2560x1440     59.95*+
   2048x1080     60.00    24.00  
   1920x1080     60.00    50.00    59.94  
   1600x1200     60.00  
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  
DP-2-1 disconnected (normal left inverted right x axis y axis)

when I disconnect the now working monitor the outputs look as follows:

inxi -Fzxu
System:
  Kernel: 5.15.41-1-MANJARO arch: x86_64 bits: 64 compiler: gcc v: 12.1.0
    Desktop: KDE Plasma v: 5.24.5 Distro: Manjaro Linux base: Arch Linux
Machine:
  Type: Desktop System: Dell product: OptiPlex 9020 v: 00
    serial: <superuser required>
  Mobo: Dell model: 0PC5F7 v: A02 serial: <superuser required> UEFI: Dell
    v: A24 date: 10/24/2018
Battery:
  Device-1: hidpp_battery_0
    model: Logitech MX Vertical Advanced Ergonomic Mouse
    charge: 55% (should be ignored) status: discharging
CPU:
  Info: quad core model: Intel Core i7-4770 bits: 64 type: MT MCP
    arch: Haswell rev: 3 cache: L1: 256 KiB L2: 1024 KiB L3: 8 MiB
  Speed (MHz): avg: 1444 high: 3363 min/max: 800/3900 cores: 1: 1095 2: 798
    3: 1452 4: 1799 5: 799 6: 1265 7: 981 8: 3363 bogomips: 54299
  Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
Graphics:
  Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics
    vendor: Dell driver: i915 v: kernel bus-ID: 00:02.0
  Display: x11 server: X.Org v: 21.1.3 driver: X: loaded: modesetting
    gpu: i915 resolution: 1440x2560~60Hz
  OpenGL: renderer: Mesa Intel HD Graphics 4600 (HSW GT2)
    v: 4.6 Mesa 22.0.4 direct render: Yes
Audio:
  Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor HD Audio
    vendor: Dell driver: snd_hda_intel v: kernel bus-ID: 00:03.0
  Device-2: Intel 8 Series/C220 Series High Definition Audio vendor: Dell
    driver: snd_hda_intel v: kernel bus-ID: 00:1b.0
  Device-3: Plantronics Plantronics Blackwire 325.1 type: USB
    driver: plantronics,snd-usb-audio,usbhid bus-ID: 3-12:5
  Sound Server-1: ALSA v: k5.15.41-1-MANJARO running: yes
  Sound Server-2: JACK v: 1.9.21 running: no
  Sound Server-3: PulseAudio v: 15.0 running: yes
  Sound Server-4: PipeWire v: 0.3.51 running: yes
Network:
  Device-1: Intel Ethernet I217-LM vendor: Dell driver: e1000e v: kernel
    port: f080 bus-ID: 00:19.0
  IF: eno1 state: up speed: 1000 Mbps duplex: full mac: <filter>
  Device-2: Ralink RT5370 Wireless Adapter type: USB driver: rt2800usb
    bus-ID: 3-7:4
  IF: wlp0s20u7 state: up mac: <filter>
Drives:
  Local Storage: total: 1.81 TiB used: 316.7 GiB (17.1%)
  ID-1: /dev/sda vendor: Intel model: SSDSC2BW480A4 size: 447.13 GiB
  ID-2: /dev/sdb vendor: Samsung model: SSD 860 PRO 512GB size: 476.94 GiB
  ID-3: /dev/sdc vendor: Western Digital model: WD1003FZEX-00K3CA0
    size: 931.51 GiB
Partition:
  ID-1: / size: 451.27 GiB used: 42.19 GiB (9.3%) fs: ext4 dev: /dev/sdb2
    uuid: b762e455-c5b1-4ddb-9df6-c76e33b2c79d
  ID-2: /boot/efi size: 299.4 MiB used: 292 KiB (0.1%) fs: vfat
    dev: /dev/sdb1 uuid: 50C8-29A4
Swap:
  ID-1: swap-1 type: partition size: 17.09 GiB used: 0 KiB (0.0%)
    dev: /dev/sdb3 uuid: 4bac82a9-c287-42b5-b706-9bcd184a826b
Sensors:
  System Temperatures: cpu: 29.8 C mobo: 27.8 C
  Fan Speeds (RPM): N/A
Info:
  Processes: 226 Uptime: 20m Memory: 15.54 GiB used: 2.4 GiB (15.4%)
  Init: systemd Compilers: gcc: 12.1.0 clang: 13.0.1 Packages: 1242
  Shell: fish v: 3.4.1 inxi: 3.3.16

xrandr
Screen 0: minimum 320 x 200, current 1440 x 2560, maximum 16384 x 16384
VGA-1 disconnected (normal left inverted right x axis y axis)
DP-1 connected primary 1440x2560+0+0 left (normal left inverted right x axis y axis) 597mm x 336mm
   2560x1440     59.95*+
   2048x1080     60.00    24.00  
   1920x1080     60.00    50.00    59.94  
   1920x1080i    60.00    50.00    59.94  
   1600x1200     60.00  
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-2-8 disconnected (normal left inverted right x axis y axis)
DP-2-1 disconnected (normal left inverted right x axis y axis)

I have tried rebooting and restarting xserver but nothing changed.
Any help is highly appreciated.

Cheers,
Davy

2

output from:
find /etc/X11/ -name "*.conf"

3 
find /etc/X11/ -name "*.conf"
/etc/X11/xorg.conf.d/30-touchpad.conf
/etc/X11/xorg.conf.d/00-keyboard.conf
4

go to system settings/compositor, and uncheck enable on startup, click apply, reboot and see if both monitors are detected

5

thanks brahma for your help, turns out I am stupid and the monitor was detected just not enabled

6

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