Consegui fazer com que o Debian 6 funcionasse com 3x gfx cards e 6 telas.
No entanto, não há suporte 3D com xinerama.
Meu xorg.conf
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 295.59 ([email protected]) Wed Jun 6 22:23:02 PDT 2012
Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
Screen 1 "Screen1" Below "Screen0"
Screen 2 "Screen2" RightOf "Screen0"
Screen 3 "Screen3" Below "Screen2"
Screen 4 "Screen4" RightOf "Screen2"
Screen 5 "Screen5" Below "Screen4"
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
Option "Xinerama" "1"
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 "Monitor1"
VendorName "Unknown"
ModelName "Samsung SMB2330H"
HorizSync 30.0 - 81.0
VertRefresh 56.0 - 75.0
Option "DPMS"
EndSection
Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor0"
VendorName "Unknown"
ModelName "Samsung SMB2330H"
HorizSync 30.0 - 81.0
VertRefresh 56.0 - 75.0
Option "DPMS"
EndSection
Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor2"
VendorName "Unknown"
ModelName "Samsung SMB2330H"
HorizSync 30.0 - 81.0
VertRefresh 56.0 - 75.0
Option "DPMS"
EndSection
Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor3"
VendorName "Unknown"
ModelName "Samsung SMB2330H"
HorizSync 30.0 - 81.0
VertRefresh 56.0 - 75.0
Option "DPMS"
EndSection
Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor4"
VendorName "Unknown"
ModelName "Samsung SMB2330H"
HorizSync 30.0 - 81.0
VertRefresh 56.0 - 75.0
Option "DPMS"
EndSection
Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor5"
VendorName "Unknown"
ModelName "Samsung SMB2330H"
HorizSync 30.0 - 81.0
VertRefresh 56.0 - 75.0
Option "DPMS"
EndSection
Section "Device"
Identifier "Device1"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 550 Ti"
BusID "PCI:2:0:0"
Screen 1
EndSection
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 550 Ti"
BusID "PCI:2:0:0"
Screen 0
EndSection
Section "Device"
Identifier "Device2"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 550 Ti"
BusID "PCI:1:0:0"
Screen 0
EndSection
Section "Device"
Identifier "Device3"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 550 Ti"
BusID "PCI:1:0:0"
Screen 1
EndSection
Section "Device"
Identifier "Device4"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 550 Ti"
BusID "PCI:3:0:0"
Screen 0
EndSection
Section "Device"
Identifier "Device5"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 550 Ti"
BusID "PCI:3:0:0"
Screen 1
EndSection
Section "Screen"
Identifier "Screen1"
Device "Device1"
Monitor "Monitor1"
DefaultDepth 24
Option "TwinView" "0"
Option "TwinViewXineramaInfoOrder" "DFP-2"
Option "metamodes" "DFP-2: nvidia-auto-select +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
Option "TwinView" "0"
Option "metamodes" "DFP-0: nvidia-auto-select +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen2"
Device "Device2"
Monitor "Monitor2"
DefaultDepth 24
Option "TwinView" "0"
Option "metamodes" "DFP-0: nvidia-auto-select +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen3"
Device "Device3"
Monitor "Monitor3"
DefaultDepth 24
Option "TwinView" "0"
Option "metamodes" "DFP-2: nvidia-auto-select +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen4"
Device "Device4"
Monitor "Monitor4"
DefaultDepth 24
Option "TwinView" "0"
Option "metamodes" "DFP-0: nvidia-auto-select +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen5"
Device "Device5"
Monitor "Monitor5"
DefaultDepth 24
Option "TwinView" "0"
Option "metamodes" "DFP-2: nvidia-auto-select +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Section "Extensions"
Option "Composite" "Disable"
EndSection