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Can you put 2 video cards in a Mac Pro?

DekeDeke Posts: 1,616
in New Users

I have a Mac Pro 3,1. I put in an EVGA 670 to run Daz with Iray. Now I'm putting in a 4gb 680, which should speed things up. Could I put in two 680's? There are two pci-e slots, but I'll have to check on power usage. But would two 4gb cards make any difference, or does the machine/Daz just use one card at a time?

Comments

  • mjc1016mjc1016 Posts: 15,001

    In general, it's not so much the memory...that isn't going to provide much of a speed boost.  What's more important are the number of CUDA cores...so yes, doubling the number of cores will make an impact...and 4 GB will give enough space to render a scene with more than just a clothed figure in it.

    As to the specifics...someone with more Mac experience (modern Macs) will need to comment on it.

  • PixelboyPixelboy Posts: 32 
    Is there a possibility to connect one or more external graphics cards via thunderbold to a iMac?
  • TotteTotte Posts: 13,670
    edited August 2015

    Deke: with 2 4GB cards you will get the power of two 680 GPUs but still only have 4GB VRAM, but that sounds like a good idea. The 680 is an old GPU, I would try the 960 4GB if I got the chance and had enough power. I got a 6G GTX-780 in my MacPro 2012 and it works really well.

    Pixelboy: There are hacks for that, but Intel "forbids" using Thunderbolt for video as it might kill thier efforts to make game developers support their on-chip GPUs. It requires stuff like kernel extensions hacking. I just wish Apple could set the foot down on Intel here, but it seems not likely. 

    There are seveeral solutions but they are only low range cards with 1 or 2 GB RAM, or the boxes you can connect can only supply power for such cards.

     

    Post edited by Totte on
  • DekeDeke Posts: 1,616

    Thanks for the info Totte.  I'd like to try two 680s (I think that is about as advanced a card that can work in a Mac Pro 3,1), but I believe I'd need to install an additional power supply. I have read they make a supply unit that will fit into  the mac case, but still tracking down the specifics. Any ideas on the power front?  A 680 wants a max of 195 W.  A Mac Pro 3,1 supplies a max of 300W for all PCI cards.

     

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