How many GPUs in the Nvidia Quadro NVS 450?

Hi,

The short version

Does the NVidia Quadro NVS 450 have more than one GPU in a single card?

The long version

I’m setting up Linux (Fedora 19) on a work computer which has a NVidia Quadro NVS 450 installed. I have set up the NVidia drivers (the nvidia module rather than nouveau) and am running Gnome 3 with 2 screens. However I’ve found that the performance is weak compared to even my old GeForce 8600 running Gnome 3. I found an old post about the Quadro NVS 450 which suggested that the card has more than one GPU and that Linux might not detect the second one properly, since I don’t know much about the card I was wondering if that was possible?

Yes, it has two GPUs in it, but it’s designed that way to run four displays. I don’t believe it supports SLI, so I think the only way to use all four display connectors on it is to set up separate X screens.

Thanks aplattner.

So I should expect 2 GPUs. Although I’m not sure what you mean by set up separate X screens.

I would like to extend this question out to, how do I configure the Quadro NVS 450 properly? In fact I’m only using 2 monitors with the card.

I did find mention of an option for use with Quadro cards:

Option "BaseMosaic" "boolean"

To be clear I imagine the setup that would make sense in my case would be like:

/-----------------------------------\
|                                   |
|  Quadro NVS 450 Card              |
|                                   |
| /-------------\   /-------------\ |
| |             |   |             | |
| |  GPU 0      |   |  GPU 1      | |
| |             |   |             | |
| |             |   |             | |
| \-------------/   \-------------/ |
|        ||              ||         |
\-----------------------------------/
         ||              ||
         ||              ||
    /----------\    /----------\
    |          |    |          |
    | MONITOR  |    | MONITOR  |
    |    0     |    |    1     |
    |          |    |          |
    \----------/    \----------/
        |  |            |  |
      <------>        <------>

Well this is my best guess at what I’m likely to want - taken from the Arch NVidia Wiki and with a number of best guesses made - I’ve not been able to test it yet, will know on Monday.

#/etc/X11/xorg.conf.d/10-monitor.conf
Section "Device"
        Identifier      "Card A"
        Driver          "nvidia"
        BusID           "PCI:1:00:0" # I need to check this and put the actual value
EndSection

Section "Device"
        Identifier      "Card B"
        Driver          "nvidia"
        BusID           "PCI:2:00:0" # I need to check this and put the actual value
EndSection

Section "Monitor"
        Identifier      "Right Monitor"
EndSection

Section "Monitor"
        Identifier      "Left Monitor"
EndSection

Section "Screen"
        Identifier      "Right Screen"
        Device          "Card A"
        Monitor         "Right Monitor"
        DefaultDepth    24
        ########Option          "SLI" "Mosaic" # Not using SLI; I think?
        Option          "Stereo" "0"
        Option          "BaseMosaic" "True"
        # I'm using 2x monitors at 1280x1024, not sure if the +1280 is correct
        Option          "MetaModes" "GPU-0.DFP-0: 1280x1024+1280+0, GPU-1.DFP-0:1280x1024+0+0"
        SubSection      "Display"
                        Depth           24
        EndSubSection
EndSection

Section "Screen"
        Identifier      "Left Screen"
        Device          "Card B"
        Monitor         "Left Monitor"
        DefaultDepth    24
        ########Option          "SLI" "Mosaic" # Not using SLI; I think?
        Option          "Stereo" "0"
        Option          "BaseMosaic" "True"
        # I'm using 2x monitors at 1280x1024, not sure if the +1280 is correct
        Option          "MetaModes" "GPU-0.DFP-0: 1280x1024+1280+0, GPU-1.DFP-0:1280x1024+0+0"
        SubSection      "Display"
                        Depth           24
        EndSubSection
EndSection

Section "ServerLayout"
        Identifier      "Default"
        Screen 0        "Right Screen" 0 0
        Option          "Xinerama" "0"
EndSection

If you’re only using two monitors, it might be easier to just plug both of them into one of the two GPUs and leave the other one unused. The ports labeled 1 and 2 go to one GPU and 3 and 4 go to the other, so just rearrange the cables if you’re using 1 & 3 or 2 & 4. I believe that ports 1 and 2 are supposed to go to the primary GPU, but the test board I have has them switched, so YMMV.

If you do want to enable multiple X screens, the easiest way is to probably run “sudo nvidia-xconfig --enable-all-gpus”. That will scan the system and insert the correct BusID lines for you.