SLI in Windows on Mac Pro?

Discussion in 'Mac Pro' started by CountlovE, May 6, 2011.

  1. CountlovE, May 6, 2011
    Last edited: May 6, 2011

    CountlovE macrumors regular

    Joined:
    Aug 17, 2007
    #1
    With two 580's is there any way to get SLI mode working? I know certain GPU applications will see both cards without SLI mode(Cuda reads device ID), but I was curious to know if a 2010 MacPro can do SLI with Nvidia drivers, or if the drivers have to be hacked.

    Thanks
     
  2. Hellhammer Moderator

    Hellhammer

    Staff Member

    Joined:
    Dec 10, 2008
    Location:
    Finland
    #3
    Mac Pros don't have the NF200 chip or SBIOS required for SLI. It might work via hack
     
  3. CountlovE thread starter macrumors regular

    Joined:
    Aug 17, 2007
    #4
    I found the SLI patch.. Will have to give it a shot. Even if it doesn't work, I heard back about V-Ray with non-SLI and multiple cards.

    This is what Vlado from Chaos Group wrote:

    "The SLI interface is designed so that several cards can exchange information and synchronize the rendering of graphics; however in OpenCL and CUDA, the application controls each GPU separately and independently so there is no need for SLI at all. V-Ray knows that you have two or more graphics cards and takes care of distributing the work among them.
    "

    As long as I can use Multiple cards without SLI, that makes me pretty happy. Thanks again for the help.
     
  4. Cindori macrumors 68040

    Cindori

    Joined:
    Jan 17, 2008
    Location:
    Sweden
    #5
    When in SLI mode, the GPU's will share VRAM.

    That maybe sounds like you will get 1GB + 1GB = 2GB, but actually it means that you will get the minimum of one of the cards. so when using two 1GB cards, the total available VRAM will be 1GB, and with 1GB and one 512MB card, you will get 512 total available vram, etc.

    So from a CUDA perspective you will want to avoid SLI
     
  5. CountlovE thread starter macrumors regular

    Joined:
    Aug 17, 2007
    #6
    Yeah, but its the same thing with CUDA. If I have both cards with 3 gigs, it will only load up to 3 gigs when rendering with V-Ray since it has to mirror the load. I will try the SLIpatch just to see if it correctly enables SLI on the Mac Pro. But its nice to know Nvidia only tries screwing everyone who uses SLI for gaming. What a greedy corporation.
     

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