I have two graphic cards from Nvidia and AMD. The GTX 970 is my primary card, but could just support up to 4 screens. Since I have more screens, they're connected to the AMD card (dedicated, no on-board).
# lspci|grep -i vga
23:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Baffin [Radeon RX 460/560D / Pro 450/455/460/555/555X/560/560X] (rev e5)
2d:00.0 VGA compatible controller: NVIDIA Corporation GM204 [GeForce GTX 970] (rev a1)
This works well on Windows 10 (dualboot). But on Ubuntu 19.10, just the AMD card works. All screens connected to the Nvidia card doesn't get any picture.
The drivers were installed
# ubuntu-drivers devices
== /sys/devices/pci0000:00/0000:00:03.1/0000:2d:00.0 ==
modalias : pci:v000010DEd000013C2sv00001458sd00003684bc03sc00i00
vendor : NVIDIA Corporation
model : GM204 [GeForce GTX 970]
driver : nvidia-driver-430 - distro non-free
driver : nvidia-driver-435 - distro non-free recommended
driver : nvidia-driver-390 - distro non-free
driver : xserver-xorg-video-nouveau - distro free builtin
And Nvidia is selected as primary card:
# prime-select query
nvidia
But when running nvidia-settings as root, it shows an empty popup and the following errors:
# nvidia-settings
ERROR: Unable to load info from any available system
(nvidia-settings:6606): GLib-GObject-CRITICAL **: 11:43:31.562: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
** Message: 11:43:31.565: PRIME: No offloading required. Abort
** Message: 11:43:31.565: PRIME: is it supported? no
The cpu is a AMD Ryzen 5 3600 without any onboard graphic. Before I had Intel with onboard GPU, where I could connect the other screens directly to the mainboard.
Edit: Driver seems in use
I found this answer and the command mentioned there shows that both drivers were already loaded:
# lspci -nnk | grep -i vga -A3 | grep 'in use'
Kernel driver in use: amdgpu
Kernel driver in use: nvidia
Edit 2: GTX 970 works when removing the AMD card
This is my current workaround, since I can at least use 4 of 5 screens on Ubuntu instead of just one screen (which was connected to the AMD card).
