2x GTX970 - SLI Mosaic - 4 monitors

Hi there,

I am having problems with making my Debian 7 (stock kernel 3.2.0-4) recognize SLI.

Xorg.0.log says:
“Failed to find a valid SLI configuration for the NVIDIA graphics device PCI:1:0:0. Please see Chapter 28: Configuring SLI and Multi-GPU FrameRendering in the README for troubleshooting suggestions.”

According to the README:


"Why does SLI or MultiGPU fail to initialize?

There are several reasons why SLI or MultiGPU may fail to initialize. Most of these should be clear from the warning message in the X log file; e.g.:

Unsupported bus type (PCIE)
The video link was not detected
GPUs do not match (2 identical graphics cards GTX970)
Unsupported GPU video BIOS
Insufficient PCIe link width (x16-x16)"

Motherboard - asus x99a (supports SLI), 2x properly powered GTX970 GPUs, bridge installed. No SLI options in the nvidia-settings.

To the best of my knowledge everything should work, or am I missing something?

Ideas? Does the driver 346.35 offer SLI support for this card? Should SLI work in SLI Mosaic mode?

Best regards.

Can you post your xorg.conf if you have one?

Note that SLI (e.g., for games) is not very well supported on Linux. Also, if your only intention of using SLI Mosaic is for the four monitors, then for now, as a workaround, you can plug all four monitors into a single 970 and drop SLI Mosaic. But then you won’t have SLI.

jwcalla: thank you very much for your reply.

For now this is what I am about to do (4 monitors -> 1 card), however, I am planning on expanding my “command centre” fairly soon - and was hoping to get 6-8 ones. For that I need two cards - I was hoping for SLI Mosaic to kick in, but I am afraid GTX970 does not support it.

All I wanted is to get 3d support on all monitors, move windows freely and maximize them to one monitors. I am afraid it won’t work as SLI Mosiac is only meant quadro cards and a few more, but not for gtx - which is more than capable - I hate politics (in this case politics of corporations)…

# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings:  version 346.35  (buildmeister@swio-display-x86-rhel47-09)  Sat Jan 10 21:57:03 PST 2015

# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig:  version 346.35  (buildmeister@swio-display-x86-rhel47-09)  Sat Jan 10 21:58:11 PST 2015

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
    Option         "Xinerama" "0"

Section "Files"

Section "InputDevice"

    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"

Section "InputDevice"

    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Samsung SyncMaster"
    HorizSync       30.0 - 81.0
    VertRefresh     56.0 - 75.0
    Option         "DPMS"

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce GTX 970"
    BusID          "PCI:1:0:0"

Section "Screen"

# Removed Option "metamodes" "GPU-76405a44-e4b4-b975-64db-cb3855c2cf46.DVI-I-1: nvidia-auto-select +1680+0, GPU-76405a44-e4b4-b975-64db-cb3855c2cf46.DVI-D-0: nvidia-auto-select +0+0, GPU-b07573ce-9abd-eb9e-1448-09002bfe5952.DVI-I-1: nvidia-auto-select +3360+0, GPU-b07573ce-9abd-eb9e-1448-09002bfe5952.DVI-D-0: nvidia-auto-select +5040+0"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "Stereo" "0"
    Option         "nvidiaXineramaInfoOrder" "DFP-0"
    Option         "metamodes" "GPU-76405a44-e4b4-b975-64db-cb3855c2cf46.GPU-0.DVI-I-1: nvidia-auto-select +1680+0, GPU-76405a44-e4b4-b975-64db-cb3855c2cf46.GPU-0.DVI-D-0: nvidia-auto-select +0+0, GPU-b07573ce-9abd-eb9e-1448-09002bfe5952.GPU-1.DVI-I-1: nvidia-auto-select +3360+0, GPU-b07573ce-9abd-eb9e-1448-09002bfe5952.GPU-1.DVI-D-0: nvidia-auto-select +5040+0"
    Option         "MultiGPU" "Off"
    Option         "SLI" "on"
    Option         "BaseMosaic" "on"
    SubSection     "Display"
        Depth       24

Ahhh yes, now I seem to recall that SLI Mosaic is limited to three monitors for Geforce cards. You can try three in SLI Mosaic to confirm that is the issue.

If having multiple monitors is more important than 3D performance, then you might be able to find some lower-end or used Quadros that have enough outputs that are maybe similarly priced? I’m pretty sure you can’t do 6-8 monitors with Geforce even on Windows.

Otherwise you might need to look at alternative vendors.

The NVS 510 is in about the same price range as a 970, but obviously does not have the same kind of 3D performance. Will you be doing CAD and stuff or do you just need a 3D desktop?

SLI Mosaic doesn’t even want to start. Based on the message:

“Failed to find a valid SLI configuration for the NVIDIA graphics device PCI:1:0:0”

After reading a lot I say it is because the graphics card is not supported by this mode. I want to have a bit of everything (3d desktop, cad and gaming under windows on the same machine). I think for the time being I will stay with one gtx970 and return the other.

Thanks for your time. ;-)

SLI Mosaic is only enabled for the professional Quadro cards. NO SLI Mosaic for geforce cards, only base mosaic which doesn’t even require the SLI bridge.

Honestly SLI and Linux is a mess right now, it doesn’t work really at all. If you do enable SLI with base mosaic off it will only run a single monitor.

Your options are to put all 4 monitors on the first 970 and don’t use base mosaic, which is my recommendation as base mosaic is simply full of bugs that will piss you off. This is the route I have taken after getting frustrated with buggy base mosaic.Or you can spread the monitors out across the 2 cards and use base mosaic, but be ready for crashes and frustration.

Multiple GPUs are a complete waste for Linux only rigs. It has been this way for a long time and Nvidia refuses to comment on when/if it will ever even work. I hope it works one day because we are starting to get the AAA games and I CAN run them @ 5760x1080 but without the help of the other 2 GPUs helping it is just a complete NO GO. So I keep windows around just for gaming these days.

Source: I have 3 970’s and 3 monitors.

Thanks ekrboi for your input.

What’s done is done. I have now 4 monitors connected to one card, the other card is about to be returned since I don’t find use for it.

I consider this topic closed.