no hdmi video output when pve booted without monitor attached

[RolandK]

hello,

i have proxmox on some s740 mini computers.

i have attached an older dvi monitor via dvi->hdmi cable and hdmi->dp adatper.

so far it's working fine.

the problem is that when i boot without the monitor attached/powered on.
attaching the monitor at a later time, it tells there is no video signal.

it's not a console blanking issue, it must have something to do with console/display initialization.

does anybody have a clue how to resolve this?

 

[CalebSnell]

Would it be possible to test with a different monitor to rule out the converters as the problem? Even if you keep the HDMI->DP adapter I think that would help.

I'll go test real quick to make sure that connecting a display after booting works at all, one minute!
*Edit, all my hosts lack integrated graphics and the GPUs are passthrough to hosts, so I can't test this. But I'm pretty sure it's worked in the past.

 

[leesteken]

Maybe the GPU does not enable certain outputs when not connected and also don't reenable them? Maybe try setting a specific output for the console?

 

[RolandK]

yes, apparently the hint with different monitor was good, at least i have changed the monitor at my home s740 system and it works without a problem

will try different monitor at the other location, too

 

[andymatei]

I find myself in a similar situation.
I have 5 nodes (Intel NUC8i7HNK and HVK) and each of them is connected into a HDMI KVM (AIMOS HDMI KVM 8 port)
In 7.4-3, when switching between them, everything went smooth, I have video signal and getting the console.

Since migration to 8.0-3 this is no longer possible. If I boot with the monitor, all OK. Then I switch to another one and it stops working with no video signal.

Any ideas? I really don't want to enforce something manually as my config changes often (it is a homelab).

Thanks in advance!