Section "ServerLayout"
    Identifier  "Layout0"
    Option      "Xinerama" "on"
    Option      "Clone"    "off"
    # You would need one screen for each monitor
    Screen   0  "Screen0"
    Screen   1  "Screen1"  RightOf "Screen0"
    Screen   2  "Screen2"  Below  "Screen0"
    Screen   3  "Screen3"  RightOf  "Screen2"
EndSection

Section "Device"
    Identifier  "Device0"
    Driver      "nouveau"
    # Actual PCI location of first card/gpu
    BusID       "PCI:3:0:0"
    # Actual connector - as reported by /sys/class/drm/card0-xx
    Option      "ZaphodHeads" "DVI-I-1"
    Option      "Monitor-DVI-I-1" "Monitor1"
    Screen      0
EndSection
Section "Monitor"
    Identifier  "Monitor1"
    Option      "PreferredMode" "1024x768"
EndSection
Section "Device"
    Identifier  "Device1"
    Driver      "nouveau"
    # Actual PCI location of first card/gpu
    BusID       "PCI:3:0:0"
    # Actual connector - as reported by /sys/class/drm/card0-xx
    Option      "ZaphodHeads" "DVI-I-2"
    Option      "Monitor-DVI-I-2" "Monitor2"
    Screen      1
EndSection
Section "Monitor"
    Identifier "Monitor2"
    Option     "PreferredMode" "1024x768"
EndSection
Section "Device"
    Identifier  "Device2"
    Driver      "nouveau"
    # Actual PCI location of second card/gpu
    BusID       "PCI:4:0:0"
    # Actual connector - as reported by /sys/class/drm/card1-xx
    Option      "ZaphodHeads" "DVI-I-3"
    Option      "Monitor-DVI-I-3" "Monitor3"
    Screen      0
EndSection
Section "Monitor"
    Identifier "Monitor3"
    Option     "PreferredMode" "1024x768"
EndSection
Section "Device"
    Identifier  "Device3"
    Driver      "nouveau"
    # Actual PCI location of second card/gpu
    BusID       "PCI:4:0:0"
    # Actual connector - as reported by /sys/class/drm/card1-xx
    Option      "ZaphodHeads" "DVI-I-4"
    Option      "Monitor-DVI-I-4" "Monitor4"
    Screen      1
EndSection
Section "Monitor"
    Identifier "Monitor4"
    Option     "PreferredMode" "1024x768"
EndSection
Section "Screen"
    Identifier  "Screen0"
    Device      "Device0"
EndSection
Section "Screen"
    Identifier  "Screen1"
    Device      "Device1"
EndSection
Section "Screen"
    Identifier  "Screen2"
    Device      "Device2"
EndSection
Section "Screen"
    Identifier  "Screen3"
    Device      "Device3"
EndSection