my X server config (dual monitor + dual GPU) rig (Intel igpu+NVIDIA)

xorg.conf

################################################################################
# Filename:      /etc/X11/xorg.conf
# Purpose:       config file for xserver
# See also:
#   /usr/share/doc/xserver-xorg/   and
#   http://wiki.x.org/wiki/Home    and
#   http://ftp.x.org/pub/X11R7.0/doc/html/index.html for information on Xorg
# Refer to the xorg.conf man page and to
# http://ftp.x.org/pub/X11R7.0/doc/html/xorg.conf.5.html
# for details about the format of this file.
#
# My config: Intel core-i7 2600 (integrated graphics)
#         Nvidia GTX-1050Ti
#         dual Monitor (Samsung_HDMI+Fujitsu_VGA)
#         Mouse
#         Keyboard
#
################################################################################
Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0"
    Screen      1  "Screen1" LeftOf "Screen0"
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
    Option         "Xinerama" "0"
EndSection

Section "Files"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    # HorizSync source: edid, VertRefresh source: edid
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Samsung"
    HorizSync       30.0 - 82.0
    VertRefresh     48.0 - 72.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "NVIDIA GeForce GTX 1050 Ti"
    BusID "PCI:1@0:0:0"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "Stereo" "0"
    Option         "nvidiaXineramaInfoOrder" "DFP-1"
    Option         "metamodes" "1920x1080_72 +0+0 {ForceCompositionPipeline=On}"
    Option         "SLI" "Off"
    #Option         "MultiGPU" "Off"
    #Option         "BaseMosaic" "on"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

### intel ###

Section "Monitor"
    # HorizSync source: edid, VertRefresh source: edid
    Identifier     "Monitor1"
    VendorName     "Fujitsu"
    ModelName      "Siemens"
    HorizSync       30.0 - 82.0
    VertRefresh     48.0 - 72.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device1"
    Driver         "intel"
    BusID "PCI:0@0:2:0"
EndSection

Section "Screen"
    Identifier     "Screen1"
    Device         "Device1"
    Monitor        "Monitor1"
    DefaultDepth    24
    Option         "Stereo" "0"
    #Option         "nvidiaXineramaInfoOrder" "DFP-1"
    Option         "metamodes" "1280x1024_72 +0+0"
    #Option         "MultiGPU" "Off"
    #Option         "BaseMosaic" "on"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection