Computers 'n Stuff: Enable SLI in Linux: My Xorg.conf as an example

I here share the resolutions for my Linux problems so they might safe somebody some time.

Saturday, June 09, 2007 parmanent link to this post

Enable SLI in Linux: My Xorg.conf as an example

The SLI mode was a little harder to enable. Here is how i got it working

Install the driver according to the nvidia howto.

sax2 -r -m 0=nvidia doesent work with SLI setup


sax2 -r -c0 -m0=nvidia

instead. assuming that your disply is hooked up to card 0. Else you can use Card 1 but card 1 will not work for SLI

Now here was that catch: when I wanted to enable SLI GPU 0 as detectd by


needs to be the same as chip0 as reported by

sax2 -p

the can be identified by ther pci adress. And the display has to be hooked up to card 0 too. else the display will be scrambled when you starup the display.

I had to change the Init Disply first to PEG(slot2) to get this accomplished.

then you type

nvidiea-xconfig --sli=on

and your set. It si imortant that the frst available Xscreen is the screen with you monitor hooked up to it if have more that one configured in you xorg.config.

Heres the sections relevant to xscreen config of xorg.conf as a reference with sli enabeled:

Section "Module"
Load "dbe"
Load "type1"
Load "freetype"
Load "extmod"
Load "glx"
Load "v4l"

Section "Monitor"
Option "CalcAlgorithm" "XServerPool"
DisplaySize 338 270
HorizSync 30-82
Identifier "Monitor[0]"
ModelName "ACER AL1714"
Option "DPMS"
VendorName "ACR"
VertRefresh 43-75
UseModes "Modes[0]"

Section "Device"
BoardName "GeForce 6800 GS"
BusID "4:0:0"
Driver "nvidia"
Identifier "Device[0]"
VendorName "NVIDIA"

Section "Screen"
DefaultDepth 24
SubSection "Display"
Depth 15
Modes "1280x1024" "1152x864" "1024x768" "800x600"
SubSection "Display"
Depth 16
Modes "1280x1024" "1152x864" "1024x768" "800x600"
SubSection "Display"
Depth 24
Modes "1280x1024" "1152x864" "1024x768" "800x600"
SubSection "Display"
Depth 8
Modes "1280x1024" "1152x864" "1024x768" "800x600"
Device "Device[0]"
Identifier "Screen[0]"
Monitor "Monitor[0]"
Option "SLI" "on"

Section "ServerLayout"
Identifier "Layout[all]"
InputDevice "Keyboard[0]" "CoreKeyboard"
InputDevice "Mouse[1]" "CorePointer"
Screen "Screen[0]"

Section "DRI"
Group "video"
Mode 0660

Nvidie Linux Driver README

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Anonymous bram said...

you said in this posting that you have to 'enable' SLI...
Does that mean:
A. both the videocards work seperately, giving 4 DVI outputs?


B. Only card 1 (if that exists) gives signal, card 2 doesn't display anything...

I'm investigating an easy way to use Distributed X to hook up to 1 displays, and form 1 big videowall... using 2 PCI-express x16 adapters in a PC drastically reduces sizing, costs and power consumption...

Let me know if you have any idea about this...

Monday, March 10, 2008 3:24:00 PM

Anonymous Vee Lee said...

Hi bram,

thanks for your question.

enabable SLI only if you actually which to use the SLI mode.

SLI (scalable linke interface) is some kind of propreitary nvidia technology to render 3D grafics on two GPUs. However, the output of two sepreate GPUs will be "bridged" to one (master) grafics adapter outmput only. The output of the other grafics adapter (slave) will diplay only junk.

However, nvidia drivers also feature a twin view (clone disply on a sceond display) and extended desktop (extend desktop to second display). This usually works on a single grafics adapter with two outputs.

In theory it should be possible to use to grafics adapters with 4 sepearate displays as well. I think the linux open source drivers for nvidia GPUs in combination with the linux X server can do this. However, I have no experience with this setup.

Good luck!

Saturday, March 29, 2008 2:55:00 AM

Blogger FredÔ!! said...

Hello there.

I know that's an old post, but I am now configuring my own sli ubuntu box.
I am wondering if this xorg's Screen Section is a good idea :
Section "Screen"
Identifier "Screen0"
Device "Device0"
Device "Device1"
Monitor "Monitor0"
DefaultDepth 24
Option "SLI" "Auto"
SubSection "Display"
Depth 24

Personaly I noticed a real graphics enhancement when starting the X session just after the gdm loging.
But I would like to precisly take a measure of that.
Do you know how to get that?!

Wednesday, January 21, 2009 5:41:00 PM

Blogger gfh said...

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Monday, July 13, 2009 2:23:00 AM


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