Second monitor is black and only works sometimes

Roman7 · 2026-09-13 20:56:20

Second monitor doesn't work after a cold boot 90% of the time, but starts working guaranteed after 1–2 reboots.

I dual boot, and on Windows 11 it's never an issue; both monitors work correctly after a cold boot.
If I boot into Win 11 first, get my second monitor working, and reboot into Arch, it continues working.

The main monitor is connected with DisplayPort - DisplayPort. The second monitor is connected with VGA - VGA - DVI-D adapter - DVI-D.

Reconnecting the cable doesn't help. It either works after boot or it doesn't. I boot into TTY, so it's not an Xorg or Wayland issue. I've tried early KMS loading of NVIDIA modules and disabling Secure Boot and keys in BIOS, but it did nothing.

I'm using an NVIDIA RTX 2060 Super with nvidia-open driver and Ryzen 5 7500F.

I'm out of ideas what to try. Any suggestions would be appreciated. Thanks!

Last edited by Roman7 (2026-09-13 21:03:31)

seth · 2026-09-13 21:19:47

* Are both outputs connected to the nvidia GPU?
* Can you connect the malfunctioning output otherwise (HDM, DP - can you switch the connections to see whether the problem follows the output or the monitor)?
* Does starting a display server (particularly X11) change anything about the situation (it will trigger a modeline change)
* Does it help to forcefully enable the output, https://www.kernel.org/doc/Documentation/fb/modedb.rst

* Ceterum censeo: 3rd link below. Mandatory.
Disable it (it's NOT the BIOS setting!) and reboot windows and linux twice for voodo reasons.

Roman7 · Yesterday 12:50:20

1) Yes, both outputs are connected to the GPU.
2) No, unfortunately VGA -> DVI-D adapter -> DVI-D GPU is the only way I can connect the monitor in question.
3) No, starting either X11 or Wayland does nothing.
4) Fast boot is disabled in Windows 11.
I also noticed that even when cold booting Windows 11, sometimes the second monitor doesn't start working right away, but instead need a couple of minutes to activate.

Finally, forcefully enabling the output did work! I forced the kernel parameter into grub

GRUB_CMDLINE_LINUX_DEFAULT="loglevel=3 quiet zswap.enabled=0 tsc=reliable clocksource=tsc video=DVI-D-1:1920x1080@60D"

However, after rebooting, the max resolution is set to 1024x768. The monitor showed up as "DVI-D-1" in KDE instead of the usual "BENQ GW2265M"
In order to fix the resolution I had to do the following.

python3 -c '
edid_hex = (
    "00ffffffffffff0031d8000000000000"
    "051601036d321c78ea5ec0a4594a9825"
    "205054000000d1c00101010101010101"
    "010101010101944380907238284080c8"
    "3500f41911000018000000ff004c696e"
    "75782023300a20202020000000fd003b"
    "3d424412000a202020202020000000fc"
    "004c696e7578204648440a2020200045"
)
with open("/tmp/edid_1080p.bin", "wb") as f:
    f.write(bytes.fromhex(edid_hex))
'

followed by

sudo sh -c 'cat /tmp/edid_1080p.bin > /sys/kernel/debug/dri/1/DVI-D-1/edid_override'

and finally one of these

echo detect | sudo tee /sys/class/drm/card1-DVI-D-1/status
echo on | sudo tee /sys/class/drm/card1-DVI-D-1/status

Also IIRC I had to use this at some point but not sure

sudo mount -t debugfs none /sys/kernel/debug

So now if the monitor doesn't activate and correctly identify at boot, I can force the ouput and then fix the resolution by using edid_override. The monitor now shows up in KDE as "The Linux Foundation Linux FHD" and has proper 1920x1080@60 resolution.
Hopefully this will be useful to someone.

Last edited by Roman7 (Yesterday 12:54:32)

seth · Yesterday 13:14:45

In order to fix the resolution I had to do the following.

You can just copy the proper edid to a disk location and load that - https://wiki.archlinux.org/title/Kernel … s_and_EDID

Please always remember to mark resolved threads by editing your initial posts subject - so others will know that there's no task left, but maybe a solution to find.
Thanks.

Arch Linux

#1 2026-09-13 20:56:20

Second monitor is black and only works sometimes

#2 2026-09-13 21:19:47

Re: Second monitor is black and only works sometimes

#3 Yesterday 12:50:20

Re: Second monitor is black and only works sometimes

#4 Yesterday 13:14:45

Re: Second monitor is black and only works sometimes

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