Bsrgvty

I am trying to get a dual-gpu setup to run on Ubuntu 18.04 (Gnome) to work. On the system installed are two gtx-1070's. The first manages two monitors with display port and one with hdmi, the second one manages two monitors with display port.

I want Ubuntu to use all 5 Monitors to expand the Desktop across all 5 Monitors, not to have one big Desktop. If possible i want to use the nvidia driver, because i occasionally play games.

Ubuntu detects the graphic cards and the connected monitors absolutely fine.

user@system:~$ lspci| grep Ge
08:00.0 VGA compatible controller: NVIDIA Corporation GP104 [GeForce GTX 1070] (rev a1)
09:00.0 VGA compatible controller: NVIDIA Corporation GP104 [GeForce GTX 1070] (rev a1)

thorben@thorben-System-Product-Name:~$ nvidia-xconfig --query-gpu-info
Number of GPUs: 2

GPU #0:
 Name : GeForce GTX 1070
 UUID : GPU-1886ccf1-635b-ef04-f7bc-ab6075ace5ee
 PCI BusID : PCI:8:0:0

 Number of Display Devices: 3

 Display Device 0 (TV-1):
 EDID Name : Samsung S22F350
 Minimum HorizSync : 30.000 kHz
 Maximum HorizSync : 81.000 kHz
 Minimum VertRefresh : 50 Hz
 Maximum VertRefresh : 75 Hz
 Maximum PixelClock : 170.000 MHz
 Maximum Width : 1920 pixels
 Maximum Height : 1080 pixels
 Preferred Width : 1920 pixels
 Preferred Height : 1080 pixels
 Preferred VertRefresh : 60 Hz
 Physical Width : 480 mm
 Physical Height : 270 mm

 Display Device 1 (TV-3):
 EDID Name : AOC 24G1WG4
 Minimum HorizSync : 160.000 kHz
 Maximum HorizSync : 160.000 kHz
 Minimum VertRefresh : 48 Hz
 Maximum VertRefresh : 144 Hz
 Maximum PixelClock : 330.000 MHz
 Maximum Width : 1920 pixels
 Maximum Height : 1080 pixels
 Preferred Width : 1920 pixels
 Preferred Height : 1080 pixels
 Preferred VertRefresh : 60 Hz
 Physical Width : 520 mm
 Physical Height : 290 mm

 Display Device 2 (TV-5):
 EDID Name : AOC 24G1WG4
 Minimum HorizSync : 160.000 kHz
 Maximum HorizSync : 160.000 kHz
 Minimum VertRefresh : 48 Hz
 Maximum VertRefresh : 144 Hz
 Maximum PixelClock : 330.000 MHz
 Maximum Width : 1920 pixels
 Maximum Height : 1080 pixels
 Preferred Width : 1920 pixels
 Preferred Height : 1080 pixels
 Preferred VertRefresh : 60 Hz
 Physical Width : 520 mm
 Physical Height : 290 mm


GPU #1:
 Name : GeForce GTX 1070
 UUID : GPU-3f0870d6-9bf2-c961-fe4a-46f8610061e0
 PCI BusID : PCI:9:0:0

 Number of Display Devices: 2

 Display Device 0 (TV-3):
 EDID Name : AOC 24G1WG4
 Minimum HorizSync : 160.000 kHz
 Maximum HorizSync : 160.000 kHz
 Minimum VertRefresh : 48 Hz
 Maximum VertRefresh : 144 Hz
 Maximum PixelClock : 330.000 MHz
 Maximum Width : 1920 pixels
 Maximum Height : 1080 pixels
 Preferred Width : 1920 pixels
 Preferred Height : 1080 pixels
 Preferred VertRefresh : 60 Hz
 Physical Width : 520 mm
 Physical Height : 290 mm

 Display Device 1 (TV-5):
 EDID Name : AOC 24G1WG4
 Minimum HorizSync : 160.000 kHz
 Maximum HorizSync : 160.000 kHz
 Minimum VertRefresh : 48 Hz
 Maximum VertRefresh : 144 Hz
 Maximum PixelClock : 330.000 MHz
 Maximum Width : 1920 pixels
 Maximum Height : 1080 pixels
 Preferred Width : 1920 pixels
 Preferred Height : 1080 pixels
 Preferred VertRefresh : 60 Hz
 Physical Width : 520 mm
 Physical Height : 290 mm

In the Nvidia driver, the two displays from the second graphic card are detected, but disabled by default. If I activate them, they are run on their own xServer (duh), which is disabled (the cursor is only a X) and unusable.

I have tried many many different things, though gdm3 seems to be quite bitchy about changing the xorg.conf. If i create a session for each display, it runs absolutely perfectly fine under xfce (like i want it to), but gdm3 won't start (black screen with movable cursor, but nothing further happens). I want to use gdm3, so this is somewhat out of the window.

After a week of searching through the internet, i found that Ubuntu now searches by default for the .config/monitors.xml file. So i tried booting from a live USB stick and it works like i want it to. After installing it on another hdd it somewhat works (the two monitors are black, but i can move my mouse over them. This appears to be an in deterministic behavior because sometimes it works).

I have also found this, but it results in an infinite reboot of the xServer. It is quite hard to get this to stop and requires precise timing.

Reinstalling the os is not really feasible for me. If i have to, i would do it, but only as an absolute last resort. Are there any other possibilities to get this to work? I am really frustrated and completely overwhelmed. What would i have to do, to get this working? How can i achieve this? Is there any good source out there, that i might have missed (which is absolutely possible)? I am sorry for your inconvenience.