X.org Configured for Intel (mode-setting) Graphics and NVIDIA (2x GPU) Compute

xorg.conf

# The purpose of this configuration is to use an integrated Intel GPU for Xorg graphical display while using NVIDIA GPU(s)
# for compute applications (NOT for actual display in Xorg).
#
# The use case for this configuration is enabling a desktop system to fully function with basic hardware acceleration while
# retaining FULL processing power from discrete GPU(s) for mining, video encoding, etc. In order to enable FULL processing
# power of NVIDIA, nvidia-settings must be used to make overclocking adjustments.
#
# This has been tested with Intel® UHD Graphics 750 (Intel® Core™ i5-11700K Processor) and two
# MSI VENTUS GeForce RTX™ 3060 2X 12G OC LHR (https://www.techpowerup.com/gpu-specs/msi-rtx-3060-ventus-2x-oc-lhr.b9132)
#
# Additionally, you DO NOT need more monitor sections for multiple monitors connected to the Intel GPU. I use dual monitors.
#
# Useful resources
# ----------------
# http://litaotju.github.io/2019/03/13/=Use-intel-for-display-nvidia-for-computing/
# https://gist.github.com/wangruohui/bc7b9f424e3d5deb0c0b8bba990b1bc5
#
# This is hand modified mixture of the output from the following commands:
# - nvidia-xconfig --cool-bits=31 --allow-empty-initial-configuration --virtual=1920x1080 --enable-all-gpus --separate-x-screens -o /tmp/xorg.conf
# - Xorg :0 -configure
#
# In order to use nvidia-settings, the NVIDIA GPU(s) use a small amount of GPU memory to create unused virtual display(s):
# $ nvtop
#   PID        USER DEV    TYPE  GPU        GPU MEM    CPU  HOST MEM 
#   486        root   0 Graphic   0%      5MiB   0%     0%    114MiB /usr/lib/Xorg :0 -seat seat0 -auth /run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
#   486        root   1 Graphic   0%      5MiB   0%     0%    114MiB /usr/lib/Xorg :0 -seat seat0 -auth /run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
#
# Identifier Naming
# -----------------
# Intel:
#   Device:  "Integrated"
#   Screen:  "PrimaryScreen"
#   Monitor: "PrimaryMonitor"
# NVIDIA 1:
#   Device:  "nvidia0"
#   Screen:  "VirtualScreen0"
#   Monitor: "VirtualMonitor0"
# NVIDIA 2:
#   Device:  "nvidia1"
#   Screen:  "VirtualScreen1"
#   Monitor: "VirtualMonitor1"

Section "ServerLayout"
        Identifier     "X.org Configured for Intel (modesetting) Graphics and NVIDIA Compute"
        Screen      0  "PrimaryScreen" 0 0
        Screen      1  "VirtualScreen0" RightOf "PrimaryScreen"
        Screen      2  "VirtualScreen1" RightOf "VirtualScreen0" # remove this line if using single NVIDIA GPU
        InputDevice    "Mouse0" "CorePointer"
        InputDevice    "Keyboard0" "CoreKeyboard"
EndSection

Section "Files"
        ModulePath      "/usr/lib/xorg/modules"
        FontPath        "/usr/share/fonts/misc"
        FontPath        "/usr/share/fonts/TTF"
        FontPath        "/usr/share/fonts/OTF"
        FontPath        "/usr/share/fonts/Type1"
        FontPath        "/usr/share/fonts/100dpi"
        FontPath        "/usr/share/fonts/75dpi"
EndSection

Section "Module"
        Load            "glx"
EndSection

Section "InputDevice"
        Identifier      "Keyboard0"
        Driver          "kbd"
EndSection

Section "InputDevice"
        Identifier      "Mouse0"
        Driver          "mouse"
        Option          "Protocol" "auto"
        Option          "Device" "/dev/input/mice"
        Option          "ZAxisMapping" "4 5 6 7"
EndSection

# Monitor for integrated Intel GPU
Section "Monitor"
        Identifier      "PrimaryMonitor"
EndSection

# (Virtual) Monitor for NVIDIA GPU 1
Section "Monitor"
        Identifier      "VirtualMonitor0"
EndSection

# remove the following section if using single NVIDIA GPU
# (Virtual) Monitor for NVIDIA GPU 2
Section "Monitor"
        Identifier      "VirtualMonitor1"
EndSection

# Device for integrated Intel GPU (modern integrated Intel GPUs should using 'modesetting' driver, NOT 'i915', i915 will be loaded anyway)
Section "Device"
        Identifier      "Integrated"
        Driver          "modesetting"
        BusID           "PCI:0:2:0"
EndSection

# Device for NVIDIA GPU 1
Section "Device"
        Identifier      "nvidia0"
        Driver          "nvidia"
        BusID           "PCI:1:0:0"
EndSection

# remove the following section if using single NVIDIA GPU
# Device for NVIDIA GPU 2
Section "Device"
        Identifier      "nvidia1"
        Driver          "nvidia"
        BusID           "PCI:2:0:0"
EndSection

# Screen for integrated Intel GPU
Section "Screen"
        Identifier      "PrimaryScreen"
        Device          "Integrated"
        Monitor         "PrimaryMonitor"
        DefaultDepth    24
        SubSection      "Display"
                Viewport        0 0
                Depth           24
        EndSubSection
EndSection

# (Virtual) Screen for NVIDIA GPU 1
Section "Screen"
        Identifier      "VirtualScreen0"
        Device          "nvidia0"
        Monitor         "VirtualMonitor0"
        Option          "AllowEmptyInitialConfiguration" "True"
        Option          "UseDisplayDevice" "None"
        Option          "Coolbits" "31" # enable all features
        # create the most minimal virtual display possible
        DefaultDepth    8
        SubSection      "Display"
                Virtual         304 200
                Depth           8
        EndSubSection
EndSection

# remove the following section if using single NVIDIA GPU
# (Virtual) Screen for NVIDIA GPU 2
Section "Screen"
        Identifier     "VirtualScreen1"
        Device         "nvidia1"
        Monitor        "VirtualMonitor1"
        Option         "AllowEmptyInitialConfiguration" "True"
        Option         "UseDisplayDevice" "None"
        Option         "Coolbits" "31" # enable all features
        # create the most minimal virtual display possible
        DefaultDepth    8
        SubSection      "Display"
                Virtual         304 200
                Depth           8
        EndSubSection
EndSection