Ubuntu – Using both nvidia and amd gpu in the same machine

1. Assuming no drivers installed and no GPUs installed in computer
2. Add AMD GPU to computer, launch Ubuntu
3. Install amdgpu-pro driver
4. Install nvidia driver (for example via sudo apt install nvidia-384)
5. Shutdown computer
6. Add NVidia card to computer, launch Ubuntu
7. Switch to console mode via Ctrl+Alt+F1
8. sudo nvidia-xconfig
9. sudo nano /etc/X11/xorg.conf
10. Comment or delete all lines except Monitor, Device and Screen sections (edit under root). Example result:

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Unknown"
    HorizSync       28.0 - 33.0
    VertRefresh     43.0 - 72.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

10. lspci | egrep -h "VGA|3D controller" - remember identifiers at the beginning of each line:

01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Hawaii XT [Radeon R9 290X] (rev 80)
02:00.0 VGA compatible controller: NVIDIA Corporation GK110 [GeForce GTX TITAN] (rev a1)

11. sudo nano /etc/X11/xorg.conf and use these identifiers:

Section "Monitor"
    ... no changes ...
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BusId          "PCI:2@0:0:0" # Add this line (identifier 2 taken from lspci output on the previous step)
EndSection

# Add similar section for AMD card:
Section "Device"
    Identifier     "Device1"
    Driver         "amdgpu"
    BusId          "PCI:1@0:0:0" # Identifier 1 taken from lspci output
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"     # This identifier should be from the GPU device connected to display (you need NVidia, so it is Device0) 
    Monitor        "Monitor0"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

12. Shutdown
13. Connect display to NVidia card
14. Launch Ubuntu - everything should work

If it doesn’t work - please provide output of lspci | egrep -h "VGA|3D controller", your /etc/X11/xorg.conf and /var/log/Xorg.0.log.

P.S. somebody please guide me how to properly "post" this answer for these similar questions:

• Mixing AMD and Nvidia graphics cards in Ubuntu
• How do I get both an AMD and NVidia GPU to not crash lightdm or hang on startup?
• Setting up CUDA on NVIDIA and AMD GPU system, starting lightdm removes nvidia binaries
• Using both nvidia and amd gpu in the same machine

To begin with: First, enable your secure boot feature in the BIOS.
Second remove and purge all your nvidia packages using:

apt-get purge nvidia*

then to remove other dependencies of the NVIDIA driver:

apt-get autoremove

Then, reboot and

apt-get install nvidia-driver-4xx

where xx is the version number.
At the end of installation process it will ask you to set a secure boot password, set it to something (but remember it and write it down).

Then proceed to reboot, which then you will be asked to enroll the key

• choose it then enter your password
• exit it and proceed to boot.
• Done