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Thread: SLI not enabled

  1. #1
    Join Date
    Aug 2017
    Posts
    2

    Cool SLI not enabled

    The NVidia control panel appears to say that I am unable to link my two 1080ti graphics cards together through SLI.

    Its a new computer and I would be shocked if its missing the SLI connector or SLI is turned off at the BIOS.

    Are there other causes for this?


    While I'm here, is there software that will evaluate GPU performance while rendering?

    If you have two monitors and two graphics cards, would you connect each monitor to its own card or combine them to keep one graphics card free for processing as I have done?

    Thanks, Jeff
    Attached Thumbnails Attached Thumbnails SLI Disabled.jpg  

  2. #2
    Join Date
    Jun 2007
    Location
    Berlin
    Posts
    754

    Default

    Hi,

    It seems that you have posted this question in the wrong forum, this is the Iray for Rhino plugin forum. The question that you have is hardware related and should be posted in an NVIDIA forum that is about hardware. Also, first check whether zour GPUs are connected with an SLI adapter. However, I can tell you that if you plan to use CUDA, it is not recommended to run with SLI. SLI can in some cases even degrade CUDA performance and won't bring a performance boost. This is only recommended when you want to use your card for 3d rendering.

    Best Regards,
    RĂ¼diger

  3. #3
    Join Date
    Aug 2017
    Posts
    2

    Default

    Hello Rudiger,
    Next time I'll put it in the hardware forum.

    My SLI is not connected and I am doing 3D rendering. Does that change your mind about the SLI connector?

    Thank you,
    Jeff

  4. #4
    Join Date
    Jun 2007
    Location
    Berlin
    Posts
    754

    Default

    Hi Jeff,

    as I said SLI is not required for SLI rendering and can at times even slow down your speed. Anyways, for rendering this is not an issue at all. SLI is targeted at gamers that need fast and good graphics but it is not beneficial for CUDA applications. If you have more questions about SLI, please ask them at https://forums.geforce.com/ as I am not an expert in this topic.

    Best Regards,
    RĂ¼diger

  5. #5
    Join Date
    Apr 2016
    Posts
    41

    Default

    I don't know if you got an answer elsewhere but I would be surprised if your new machine HAS the SLI connector--and that seems to be what the control panel is telling you is missing--as that has to be ordered separately at some non trivial cost for this gen of cards, the whole SLI thing is not being pushed so much with this generation.

    I have 2 970s in SLI, with the connector cable, and SLI works quite fine on the games that use it and leaving it turned on seems to have no harm on the stuff like iRay that doesn't.

    You might as well connect your screens to one card and leave the other for CUDA processing alone, it will in theory be faster with that overhead removed.

  6. #6
    Join Date
    Dec 2015
    Location
    Devon, UK
    Posts
    97

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    I have the SLI cable connected on my two GTX 760Ti's for when I play gaming (very rarely, but in the off chance that I do, I keep it connected). However, when rendering using iRay, I switch SLI off in the Nvidia control panel. I also use both cards for rendering even though one of them is driving a 30" 4K monitor. It works fine.

    I would be interested to see if iray runs faster if you disable SLI in the control panel jcarruthers. I think that I did a before and after test and believe that iray does run faster with SLI disabled, but physically connected, in my case. I have seen no real difference between physically connected via SLI and with SLI disabled to SLI disconnected.

    Apologies for hijacking this thread Rudiger. You are right that this should be in the hardware forum.

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