No display output if monitor is powered on after computer

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Description of problem:

I would like to be able to do something like this.

  1. Turn on my computer without a monitor powered on/connected.
  2. (Optional) Do stuff with it over the network, like using it as a file server.
  3. Decide later that I want to use it with a monitor, and connect one/turn one on.

Attempting this results in no display signal being produced until I restart the computer.

Version-Release number of selected component (if applicable):

gdm-41.3-1.fc35.x86_64
GNOME 41.3

How reproducible: 100%

Steps to Reproduce:

  1. Make sure both the computer and monitor are powered off and connected via DisplayPort.
  2. Power the computer on. Wait for it to boot (≈30 seconds).

Steps to Reproduce (alternative):

  1. Make sure that:
    • The computer is powered off
    • The monitor is powered on
    • These devices are not connected
  2. Power the computer on. Wait for it to boot (≈30 seconds).
  3. Connect the monitor to the graphics card via DisplayPort.

Actual results: Monitor reports “No Signal.”

Expected results: GNOME Display Manager (login screen) is displayed.

Additional info:

Graphics card: Sapphire Radeon RX 5700 XT Nitro+

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My understanding, when the system boot up, it will probing the available resources to be uses until login screen (showing display manager). Then after we login, it will uses hot plug detection.

For your case, when you turn on the computer and the monitor off, it will assumed there no monitor.

I have dual monitor setup for my laptop. The second monitor connected via HDMI. If I connect the second monitor without power it on (the AC power still connected) during the boot, my laptop will not recognize my second monitor even after I login.

To make it recognized by my laptop, I need to unplug the HDMI and plugin again (some time also need to reload everything).

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