Second DVI port stopped working


I have a very strange problem with the second DVI port on my GeForce 5601Ti with ubuntu.

Both xrandr and nvidia control panel show second monitor disconnected (monitor and cable verified on first DVI port), even with clean install of OS (even tried different versions of Ubuntu).
Both DVI ports and monitors used to work fine on 16.04 and 18.04. Then something happen and the second DVI port shows disconnected.
After trying EVERYTHING I could think of (and everything suggested on various forums), I thought the card was broken and purchased a new (a 1050Ti) but still have the same problem. I’ve booted on a live-CD with both 16.04 and 18.10 to test with a clean install but both cards show disconnected on the second port (DVI on the 560 and HDMI on the 1050). The motherboard is a MSI B350.
Please help!
Soren Svensson

nvidia-bug-report.log.gz (79.5 KB)
nvidia-bug-report-2.log.gz (569 KB)
nvidia-bug-report-1050-connected.log.gz (557 KB)
nvidia-bug-report-1050-not-connected.log.gz (566 KB)

Please run as root and attach the resulting .gz file to your post. Hovering the mouse over an existing post of yours will reveal a paperclip icon.

Unfortunately, your log is flooded with errors from AMD-Vi/IOMMU. Please disable it in bios and create a new nvidia-bug-report.log with a new post so it will be noticed.

I fixed it and uploaded a new file

So if you swap connectors at the card, the Anchor monitor comes alive?

Yes it does. Another thing is, if I have both monitors hooked up at boot, it’ll not finish the boot and turn on primary monitor until I unplug the secondary monitor.

Now that’s really weird. Can you please boot with the second monitor attached, wait some time, then remove the monitor so boot continues, reattach the monitor and create a new nvidia-bug-report.log ?

I tried it but it didn’t work with the 1050Ti, the boot never continued after I disconnected the second monitor. It must have been specific to the 560Ti card.

The previous loggs have been created while using the 560ti, can you attach a new one with the 1050ti and the second monitor attached after boot?

Here’s one log before I connected the second monitor and one after.
Notice that while the log script was running (towards the end), the resolution on my primary monitor suddenly switched from 1920x1200 to 954x540 and I had to reboot to get back to full resolution. I tried both ubuntu and nvidia control panel and neither knew about any higher resolution.

Two things to try:

  • Remove your xorg.conf and check if anything changes
  • Boot a live image with only the second monitor attached.
    BTW, if only the second monitor is attached on boot, does it display bios POST messages and bios menu?

Good news, I’ve found the problem!

Turns out, it was the second monitor?!

If I had it connected HDMI (second port) to HDMI (monitor) it was not detected.But if I moved it to the first port (with a DVI-HDMI adapter) it worked.
I tested first monitor on second port and second monitor on first port, also worked.
Finally I tried the HDMI-DVI adapter at the second monitor (using the DVI input) and it worked!

Second port, HDMI-HDMI to second monitor. FAIL
First port, DVI-HDMI to second monitor. OK
Second port, HDMI-DVI to second monitor. OK
First monitor works in all ports.

Why haven’t I tried this before? Well, my second monitor is mounted high up on a wall with a long HDMI cable.

Thanks to generix for helping me with this.