Monitor receives no signal in GUI mode

Sylvain Hubert

12/26/23, 5:08 PM

This weird problem might not concerns Ubuntu, but is rather only solvable from Ubuntu.

Setup:

New ThinkStation with empty disks, cpu=i9-12900K, gpu=NVIDIA RTX A4000
Ubuntu 22.04 live USB plugged in
Tried multiple monitors from different vendors, making no difference
Tried HDMI cable + DP cable + USB type-c cable, making no difference

Symptoms:

After powering up the machine, the monitor stays sleeping and receives no signal for ~1min, not even showing BIOS/UEFI stuffs, leaving me clueless of what's going on, until it suddenly shows the Ubuntu splash screen with the white spinning circle.
So far, Ubuntu 22.04 live USB has been the only distro that managed to light up the monitor and let it show anything. No other distro succeeded in that, not Cent, not Arch, not even Ubuntu 20.04.
When the splash screen has ended, the monitor receives no more signal and goes to sleep again. My bet is that the X has started but the monitor or the graphic card somehow doesn't work well with GUI.
So I pressed Ctrl+Alt+F2. Miraculously, the monitor lights up again with a CLI where I can inspect stuffs.
But if I press Ctrl+Alt+F1 to go back to GUI, the monitor sleeps. Or if I run startx from the CLI, the monitor sleeps.

So it seems that the new machine can't properly display BIOS/UEFI or the Ubuntu GUI, and the only chance for me to debug this problem is from the CLI of Ubuntu 22.04 live USB.

My question is: 1. What could be the cause of this problem? 2. Where does one usually look at in Ubuntu if the monitor receives no signal? Is there some kind of log for this?

138

0 + 5

nvidia

monitor

22.04

Matias N Goldberg

12/26/23, 6:15 PM

You didn't any post HW info (cpu? gpu?). Also, silly advise but make sure you didn't plug to the iGPU instead of the dGPU slots. If you did plug it correctly, try the iGPU's instead

Sylvain Hubert

12/26/23, 7:04 PM

Info updated. Though the slots doesn't seem to distinguish between i/d-GPU.

Matias N Goldberg

12/27/23, 2:28 AM

Check `lsmod` to see whether you're using nouveau (bad) or nvidia module (good, it's the proprietary one). Also check `/var/log/Xorg.0.log` to see if it has something useful

Matias N Goldberg

12/27/23, 2:36 AM

"Though the slots doesn't seem to distinguish between i/d-GPU." Do you mean you tried both and got the same results, or that you didn't know which ones were d- and which ones i-GPUs?

Sylvain Hubert

12/27/23, 9:31 AM

You're right, they're indeed distinguished. There're 7 slots for monitors and I missed 4 of them. Many thanks and sorry for the stupid question :-/

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Monitor receives no signal in GUI mode

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