Originally published on eve.gd on 15 April 2014, last updated 6 September 2026.
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OK, so this was utterly painful and I needed to share what finally worked for me. I have 2 x Nvidia GTX480 cards. I have 3 x monitors. I wanted to be able to run all three off the same box, using it as a single X Screen (i.e. so I can move windows between screens and it acts correctly). No matter what I tried, it wouldn't let me do so with the proprietary driver. I asked on Stack Exchange and got somewhere closer. Here's what worked:
My XConfig looks like this:
Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0"
EndSection
Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor1"
VendorName "Unknown"
ModelName "Ancor Communications Inc ASUS VS247"
HorizSync 24.0 - 83.0
VertRefresh 50.0 - 75.0
Option "DPMS"
EndSection
Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor0"
VendorName "Unknown"
ModelName "LG Electronics W2243"
HorizSync 30.0 - 83.0
VertRefresh 56.0 - 75.0
Option "DPMS"
EndSection
Section "Monitor"
# HorizSync source: unknown, VertRefresh source: unknown
Identifier "Monitor2"
VendorName "Unknown"
ModelName "AOC LM720/LM720A"
HorizSync 30.0 - 83.0
VertRefresh 55.0 - 75.0
Option "DPMS"
EndSection
Section "Device"
Identifier "Device1"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 480"
BusID "PCI:1:0:0"
EndSection
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 480"
BusID "PCI:1:0:0"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
Option "Stereo" "0"
Option "MultiGPU" "Off"
Option "SLI" "on"
Option "SLIMosaic" "True"
Option "BaseMosaic" "True"
Option "MetaModes" "GPU-1.CRT-0: 1280x1024+0+0, GPU-0.CRT-0: 1920x1080+1280+0, GPU-0.DFP-2: 1920x1080+3200+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Totally weirdly, you don't need to have more than one device listed (my second card is at "PCI:1:0:0").
Note also that, despite this then yielding two providers, when it's working xrandr 1.4 (which supports multiple GPUs) only lists 1 provider:
xrandr --listproviders Providers: number : 1 Provider 0: id: 0x279 cap: 0x1, Source Output crtcs: 4 outputs: 10 associated providers: 0 name:NVIDIA-0"
Anyway, it now works!
This reference list has been generated, in many cases, through an automated process and may therefore contain errors or incomplete metadata. It is provided purely as assistance for finding the items mentioned within this post.
1. Stack Exchange: xrandr dual Nvidia triple-head question <http://unix.stackexchange.com/questions/123862/how-can-i-get-xrandr-to-detect-both-nvidia-cards-2-x-gtx480-triple-head>
Martin Paul Eve
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