Hello

I had both monitors working, stopped using the PC for a while and have now started it back up again, The second monitor won't display once the OS starts

It does output to both monitors for the bios post screen but once the OS starts it only displays on the DVI port and not either of the HDMI ports

I had Fedora 33 installed when the issue started, upgraded to 34 with the same issue, did a clean install of 34 and still have the same issue (I have run a dnf update)

Checked output of: lspci -v
Kernel driver in use: amdgpu
Kernel modules: amdgpu


So I thought it was the the OS because the bios shows on the HDMI monitor, but I tried the cable on 2 other laptops (one with fedora 33 and one with windows 10) neither displays anything then used a different cable on the original PC (different HDMI cable) and it works. So it seems to be the cable, but seems really odd that it is showing the bios post right?

Just curious if anyone else has had a similar issue in the past

I don't completely understand your question: so you have this working and it was just a bad cable? Or you have an intermittent signal from the machine depending on context? If the former, then 'so what?' because you fixed it, if the later, it may be that the cable in question has trouble with whatever higher resolution (and thus bandwidth) you're asking to be sent over it - while all HDMI cables use the same connector they are not all capable of the same resolution(s). Usually the POST messages are running at a pretty low overall resolution (like 640x480 or 800x600 or something) but if you're attempting to run 4K or beyond on an old HDMI cable it may not be capable.