# lspci -nn|grep VGA
01:00.0 VGA compatible controller [0300]: NVIDIA Corporation G86 [Quadro NVS 290] [10de:042f] (rev a1)
02:00.0 VGA compatible controller [0300]: NVIDIA Corporation G86 [Quadro NVS 290] [10de:042f] (rev a1)
# ls -l /sys/class/drm/
total 0
lrwxrwxrwx 1 root root    0 Mar 11 09:57 card0 -> ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0
lrwxrwxrwx 1 root root    0 Mar 11 09:57 card0-DVI-I-1 -> ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-DVI-I-1
lrwxrwxrwx 1 root root    0 Mar 11 09:57 card0-DVI-I-2 -> ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-DVI-I-2
lrwxrwxrwx 1 root root    0 Mar 11 09:57 card1 -> ../../devices/pci0000:00/0000:00:1c.0/0000:02:00.0/drm/card1
lrwxrwxrwx 1 root root    0 Mar 11 09:57 card1-DVI-I-3 -> ../../devices/pci0000:00/0000:00:1c.0/0000:02:00.0/drm/card1/card1-DVI-I-3
lrwxrwxrwx 1 root root    0 Mar 11 09:57 card1-DVI-I-4 -> ../../devices/pci0000:00/0000:00:1c.0/0000:02:00.0/drm/card1/card1-DVI-I-4
lrwxrwxrwx 1 root root    0 Mar 11 09:57 controlD64 -> ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/controlD64
lrwxrwxrwx 1 root root    0 Mar 11 09:57 controlD65 -> ../../devices/pci0000:00/0000:00:1c.0/0000:02:00.0/drm/controlD65
lrwxrwxrwx 1 root root    0 Mar 11 09:57 ttm -> ../../devices/virtual/drm/ttm
-r--r--r-- 1 root root 4096 Mar 11 09:57 version
# vim /etc/X11/xorg.conf
Section "ServerLayout"
    Identifier  "Layout0"
    Option      "Xinerama" "on"
    Option      "Clone" "off"
    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"
    BusID       "PCI:1:0:0"
    Option      "ZaphodHeads" "DVI-I-1"
    Screen      0
EndSection

Section "Device"
    Identifier  "Device1"
    Driver      "nouveau"
    BusID       "PCI:1:0:0"
    Option      "ZaphodHeads" "DVI-I-2"
    Screen      1
EndSection

Section "Device"
    Identifier  "Device2"
    Driver      "nouveau"
    BusID       "PCI:2:0:0"
    Option      "ZaphodHeads" "DVI-I-3"
    Screen      0 
EndSection

Section "Device"
    Identifier  "Device3"
    Driver      "nouveau"
    BusID       "PCI:2:0:0"
    Option      "ZaphodHeads" "DVI-I-4"
    Screen      1
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