xorg.conf for triple monitors (one portrait, two landscape) with two nvidia video cards.

xorg.conf

# Configuration file for triple-head setup using a GT610 (first slot) and a 8500GT (second slot)
#
# Physical layout like this (not to scale).
#          _________
#         |         |
#         |   20"   |
#  _____  |         |
# |r 23"| |_________|
# | o   |  ____________
# |  t  | |            |
# |t  a | |            |
# | e   | |    23"     |
# |__d__| |____________|
#
#
# Use with care and
# * nvidia-313.x
# * xorg-server 2:1.11.4-0ubuntu10.8
#
#
Section "ServerLayout"
    Identifier     "Layout0"

    Screen      0  "ScreenTop" 0 0
    Screen      1  "ScreenLeft" LeftOf "ScreenRight"
    Screen      2  "ScreenRight" Below "ScreenTop"

    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
    Option         "Xinerama" "1"
EndSection

Section "Files"
EndSection

Section "Extensions"
    Option         "Composite" "Disable"
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     "MonitorTop"
    VendorName     "Unknown"
    ModelName      "Eizo EV2335W"
    HorizSync       31.0 - 81.0
    VertRefresh     55.0 - 76.0
    Option         "DPMS"
EndSection

Section "Monitor"
    # HorizSync source: unknown, VertRefresh source: unknown
    Identifier     "MonitorLeft"
    VendorName     "Unknown"
    ModelName      "LG Electronics LX20D"
    HorizSync       0.0 - 0.0
    VertRefresh     0.0
    Option         "DPMS"
EndSection

Section "Monitor"
    # HorizSync source: unknown, VertRefresh source: unknown
    Identifier     "MonitorRight"
    VendorName     "Unknown"
    ModelName      "Eizo EV2335W"
    HorizSync       0.0 - 0.0
    VertRefresh     0.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "DeviceTop"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce 8500 GT"
    BusID          "PCI:2:0:0"
EndSection

Section "Device"
    Identifier     "DeviceLeft"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce GT 610"
    BusID          "PCI:1:0:0"
    Screen          0
EndSection

Section "Device"
    Identifier     "DeviceRight"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce GT 610"
    BusID          "PCI:1:0:0"
    Screen          1
EndSection

Section "Screen"
    Identifier     "ScreenTop"
    Device         "DeviceTop"
    Monitor        "MonitorTop"
    DefaultDepth    24
    Option         "Stereo" "0"
    Option         "metamodes" "nvidia-auto-select +0+0"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

Section "Screen"
    Identifier     "ScreenLeft"
    Device         "DeviceLeft"
    Monitor        "MonitorLeft"
    DefaultDepth    24
    Option         "Stereo" "0"
    Option         "metamodes" "CRT: nvidia-auto-select +0+0 {Rotation=left}"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

Section "Screen"
    Identifier     "ScreenRight"
    Device         "DeviceRight"
    Monitor        "MonitorRight"
    DefaultDepth    24
    Option         "Stereo" "0"
    Option         "nvidiaXineramaInfoOrder" "DFP-1"
    Option         "metamodes" "DFP: nvidia-auto-select +0+0"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection