I am currently upgrading my system from one video card and 3 monitors to two video cards and 4 monitors, but I'm unable to make the fourth monitor work on the second video card. The other three monitors on the first video card all work fine.
The OS detects both video cards as well as all the monitors as expected, but I'm getting no video output on the fourth monitor that is connected on the secondary video card.
In my current setup I am using the latest nvidia drivers that I installed via ppa/metapackage, version 470.63.01, cuda 11.4.
I can't figure out what I need to modify in ubuntu to enable the output on the second video card/fourth monitor.
Trying to enable the fourth monitor via the display settings does not enable it and stays powered off.
I have also edited the /etc/X11/xorg.conf file manually to add additional "Device", "Monitor" and "Screen" sections, but this does not seem to do anything.
The original xorg.conf created during installation when only one video card and one monitor were present only has entries for one Screen, one Monitor, and one Device (although all three monitors work).
So after adding the second video card and fourth monitor, this file does not seem to be updated automatically, which is is why I tried editing it manually.
I also tried the nvidia-settings program as administrator to setup a new screen for the second video card, but this messes up the configuration of all the monitors and I still can't see anything on the fourth monitor. This program modifies the same xorg.conf file.
The odd thing is when I boot from a live CD with the same ubuntu version, as well as with xubuntu 20.04, everything shows up and works fine.
I can even go into the display settings directly and I can set up and position all four monitors and everything works perfectly.
When I compare the /var/log/Xorg.0.log file from the live CD against my current installation, I notice that the live CD has no xorg.conf and everything is detected automatically.
The driver it uses is different too, but I can't tell what it is. My installation seems to be loading the nvidia-470 driver but also mentions the nouveau driver. Maybe they are the same since I installed them via the ppa.
I don't know if I need to revert back to an older driver or use the default one that is on the live CD somehow. I would need to read up on how to do this since it would be the first time I would be trying this.
Aside from that, I'm not sure where else I need to look to debug my problem so that I don't have to reinstall from scratch.
I've looked at the output of the following for clues to no avail:
sudo lshw -C display
xrandr
/etc/X11/xorg.conf (original from installation and nvidia-settings modified versions)
/var/log/Xorg.0.log
The only thing that seems inconsistent is between DP-1 from first card and DP-1-0 from the second card, where the frequencies/refresh rates are different/absent (the two monitors are the same make and model for these ports):
1st card:
DP-1 connected primary 1920x1080+0+721 (normal left inverted right x axis y axis) 527mm x 296mm
1920x1080 60.00*+ 59.94 50.00 60.00 50.04
2nd card:
DP-1-0 connected (normal left inverted right x axis y axis)
1920x1080 60.00 +
The nvidia-settings (Nvidia X Server Settings) program shows that there is no connection link for monitor 4, but shows single link for the other monitors on the first videocard.
Any insight would be greatly appreciated.
Computer setup:
- I'm unning Ubuntu Studio 20.04 with all the latest updates as of 2021-08-26. Ubuntu studio is Ubuntu with the xfce desktop environment and lightdm window manager.
- The computer is an HP z620 workstation with one processor and 32GB ram
- The two video cards are: nvidia quadro K4000 (primary pci16 slot) and nvidia quadro K2000 (secondary pci16 slot)
- 4 monitors: 3 on primary video card, 1 on secondary card (all monitors are functional)
- Both video cards work stand alone with three monitors directly connected (I tried each video card separately with three monitors to confirm that the cards were both fine and that all ports were functional)
- Bios settings don't indicate any special settings for the video cards aside from which one I want as the primary one, and I am using the latest bios image available
- Kernel version: Linux hpz 5.4.0-81-lowlatency #91-Ubuntu SMP PREEMPT Thu Jul 15 20:15:41 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
- Release version: Ubuntu 20.04.3 LTS
