5 Replies Latest reply on Aug 17, 2018 11:12 AM by misterj

    2700x - Multiple GPU?

    shujx4

      I've read that CPUs have PCIe lanes and that those are used by the GPU.

       

      1.- So if Ryzen 2700x has 20 PCIe lanes, does that mean I can only have one x16 GPU (or 2 x8)?

       

      2.-  Does that mean if I want two x16 I need a 40 PCIe lanes processor?

       

      3.- If that's the case, why does having multiple graphics cards on a 20 PCIe lane CPU actually makes a difference while GPU rendering?

       

      (About the third question, here's a post showcasing it)

       

      Best Hardware for GPU Rendering Octane Redshift Vray - CG Director

       

      4.- If it doesn't affect negatively having multiple graphics cards on a 20 PCIe lane CPU (such as Ryzen 2700x) while doing GPU rendering, then, when does it matter? (negatively)

       

      Thank you

        • Re: 2700x - Multiple GPU?
          misterj

          shujx4, 20 PCIe lanes seems awfully low.  Where did you get that number?  Please post your system specifications.  Thanks and enjoy, John.

            • Re: 2700x - Multiple GPU?
              shujx4

              Excuse me if I said something incorrect (I know little on the topic), I'm trying to build a PC around AMD Ryzen 7 2700X and upon google searching I found different answers saying that CPU has 20 - 24 PCIe lanes.

               

              My whole post can be put into a single question:

               

              When does dual x16 outperforms significantly a dual x8?

                • Re: 2700x - Multiple GPU?
                  misterj

                  shujx4, you are correct and I hope you did not think I was criticizing you it just seems low to me.  Here is the quote I found: "16 (Free) + 4 (NVMe)".  I have a Threadripper 1950X with 64 lanes (I think 60 free).  I know little about graphics, but what you are really asking does the computing power of the two GPUs make it better that the lanes to move data.  I have done no mining but those rigs use many GPUs, maybe 10 to 20 or more.  So they use little data but lots of computing.  They use only one or two lanes per GPU.  I hope a graphics person will respond or you could post in the Graphics forum here.  Good luck and enjoy, John.

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