4 Replies Latest reply on May 20, 2010 7:35 AM by emuller

    4x HD5970 Support?

    afo
      It is possible to work with 4 HD5970 in one system?

      dear people,

      I am not sure if this is the right forum to ask, so please apologize and direct me to the right place if not.

      Currently I am working with 2x HD5970 for an openCL application, and I am using a MSI 790FX-GD70 motherboard. It has 4 PCIe slots and claims to support up to 4 graphic cards.

      But the MSI web site says that when you use 2 PCIe slots, they are at 16x, but when you use 4 PCIe slots, the speed of each one is 8x.

      (http://www.msi.com/index.php?func=proddesc&maincat_no=1&cat2_no=171&prod_no=1740)

      So my question is: Can I work with 4x HD5970 at PCIe 8x (with a transfer speed penalty), or HD5970 can only work at PCIe 16x?

      Thanks in advance for any insight about this

      best regards,

      Alfonso

        • 4x HD5970 Support?
          emuller

          See these threads:

          http://forums.amd.com/forum/messageview.cfm?catid=328&threadid=122135

          http://forums.amd.com/devforum/messageview.cfm?catid=328&threadid=107726

          http://forums.amd.com/devforum/messageview.cfm?catid=328&threadid=103174

          In my experience, using a dual GPU card in a 8x slot is no problem (proved by putting 2 4870x2 in a 790fx system with a gtx260).  I would love if someone from AMD would correct me here, but all reports seem to point to driver issues with more that 4 GPUs in one system.  For example, 2 4850x2 work, 2 4850x2 and 1 4850 (5 GPUs) does not work (under various linuxes, hard lock @ X start).

          NB:  I have not tried this recently with >4 5800 series GPUs and a 890fx mobo, and 10.4 drivers ... please if someone gets this to work, lets us know!!

           

           

           

            • 4x HD5970 Support?
              nou

              it is just games but it works. http://www.techpowerup.com/reviews/AMD/HD_5870_PCI-Express_Scaling/1.html even with only 1x

              i think i seen someone post that more than 4 GPU are working now but it is slow.

              • 4x HD5970 Support?
                afo

                Thanks a lot for the links.

                About that, I have seen in other posts that you need to create an individual context for every GPU and disable crossfire in order to have correct results in the second GPU in HD5970 cards.

                Using CLInfo, when I have crossfire enabled, I see one CL_DEVICE_TYPE_CPU and four CL_DEVICE_TYPE_GPU (the correct configuration), but if I disable crossfire in CCC, I see one CL_DEVICE_TYPE_CPU, and only three CL_DEVICE_TYPE_GPU. So, how can I disable crossfire and still have four CL_DEVICE_TYPE_GPU?

                My configuration:

                WinXP SP3 32 bits

                catalyst 10.4

                AtiStream 2.1

                Visual Studio 2008 SP1

                2xHD5970 with MSI crossfire link cable

                MSI 790FX-GD70

                Phenom II 945

                2GB DDR3 1066

                No Overclocking, Samples compile fine, I used to work with a HD4350.

                I will really apreciate any insight about this

                best regards,

                Alfonso

                  • 4x HD5970 Support?
                    emuller

                     

                    Originally posted by: afo Thanks a lot for the links.

                     

                    About that, I have seen in other posts that you need to create an individual context for every GPU and disable crossfire in order to havecorrect results in the second GPU in HD5970 cards.

                     

                    Indeed: crossfire must be disabled, 1 context per GPU, *and* generally one thread per context as per docs.

                     

                     


                    Using CLInfo, when I have crossfire enabled, I see one CL_DEVICE_TYPE_CPU and four CL_DEVICE_TYPE_GPU (the correct configuration), but if I disable crossfire in CCC, I see one CL_DEVICE_TYPE_CPU, and only three CL_DEVICE_TYPE_GPU. So, how can I disable crossfire and still have four CL_DEVICE_TYPE_GPU?

                     

                    My configuration:

                     

                    WinXP SP3 32 bits

                     

                    catalyst 10.4

                     

                    AtiStream 2.1

                     

                    Visual Studio 2008 SP1

                     

                    2xHD5970 with MSI crossfire link cable

                     

                    MSI 790FX-GD70

                     

                    Phenom II 945

                     

                    2GB DDR3 1066

                     

                    No Overclocking, Samples compile fine, I used to work with a HD4350.

                     

                    I will really apreciate any insight about this

                     

                    best regards,

                     

                    Alfonso

                     

                    On Linux it is no problem.  On Windows I have no idea, sorry.