3 Monitor SetUp using 2 SLI Nvidia Cards on Fedora

I've been struggling around with /etc/X11/xorg.conf while the not quite obvious solution was quite simple. Perhaps I can save someone else's time.

As a prerequesite you should have the kmod nvidia driiver (rpmfusion) or the proprietary driver installed. I've tested this on Fedora 20 but it should also work on 18 or 19.

Just run this as root:

nvidia-xconfig –base-mosaic –metamodes="GPU-0.DFP-0: 1920×1200+0+0, GPU-0.DFP-1: 1920×1200+1920+0, GPU-1.DFP-0: 1920×1200+3840+0"

I'm using 3 Full-HD monitors, so the resolution of each is 1920x1200px. GPU-0 is the first graphic card, GPU-1 the second. So GPU-0.DFP-0 is my first monitor on the first graphic card and so on. As the 3 monitors are besides each other, the second screen starts at position 1920+1920, the third monitor starts at 1920 + 1920 + 1920, that's why I'm adding 1920px for the second and 3840 for the third monitor on the horizontal axis. Having 1920×1200+0+0, the first +0 represents the horizontal adjustment, the second +0 the vertical adjustment.

The above command should create you a file like this or similar:

Section "ServerLayout"
    Identifier     "Default Layout"
    Screen         "Default Screen" 0 0
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"

Section "InputDevice"
    # generated from default
    Identifier     "Keyboard0"
    Driver         "keyboard"

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

Section "Device"
    Identifier     "Videocard0"
    Driver         "nvidia"

Section "Screen"
    Identifier     "Default Screen"
    Device         "Videocard0"
    Option         "BaseMosaic" "True"
    Option         "MetaModes" "GPU-0.DFP-0: 1920x1200+0+0, GPU-0.DFP-1: 1920x1200+1920+0, GPU-1.DFP-0: 1920x1200+3840+0"
    SubSection     "Display"
        Modes      "nvidia-auto-select"

Just restart your X-Server or reboot your machine and you should see your monitors light up!