13 Replies Latest reply on Jul 30, 2015 7:55 PM by n4cr

    CFX Fury X PCI-E lane requirements

    n4cr

      Hello. Building a new 4K CFX Fury X system.

      Have some questions regarding CPU choice and PCI-E lanes therefore..

       

       

       

      AMD recommends the following;

       

      Quote:

       

        'These recommendations apply to both single-card and dual-card installations:
      • PCI Express-based PC with at least one ×16 lane graphics slot available on the
      motherboard' 

      Interestingly, that's the very first recommendation they make, without specifying what the second card should run at.

       

       

      Have since seen a benchmark between i7-4790K vs i7-5930K + SLI 980 Ti in 3 Games @ (4K) i7-4790K vs i7-5930K + SLI 980 Ti in 3 Games (4K) - YouTube

      The 5930 was significantly faster, considering GPUs are the same...

       

      I wonder if the same will be noticeable with the Fury X in CFX on an X99 board... especially with HBM and way AMD card operates, perhaps an even greater difference.

       

      Can anyone from AMD confirm that the extra lanes will be of benefit? I'm now leaning towards getting the 5930 + CFX Fury X for this reason.. Cheers

        • Re: CFX Fury X PCI-E lane requirements
          goodplay

          amdmatt

          Could be of help re mobo.

          • Re: CFX Fury X PCI-E lane requirements
            Thanny

            It's hard to see why you think comparing a quad-core processor with a hexa-core processor has anything to do with the number of PCIe lanes.

             

            That said, fewer lanes means slower transport.  Both for feeding the card from the CPU, and communicating between cards with CrossFire.  So getting a full 16 lanes for each card is desirable.  However, the performance impact will likely be negligible.  All tests of the difference between 16 lanes and 8 lanes (or between PCIe 2.0 and 3.0, which amounts to the same thing in terms of throughput) invariably show very minor differences.  I recall reading about a couple tests which didn't even show a major loss of performance with 16x/4x setups.

              • Re: CFX Fury X PCI-E lane requirements
                n4cr

                Hey, thank you for this, I understand completely and and also have seen these numbers.

                 

                Reason is, most games are not CPU bound, or dual core in quite a few cases, so same architecture and same clockspeed, shouldn't' make too much difference, especially not what is shown there. Thing is, no one has done this with the CFX Fury X setup yet, plus AMD specifies 16x without being clear on additional cards (I assume they mean 16x for all!) - so this is why I ask. HBM may be much more happy with low latency and/or high bandwidth, it is a completely new approach, hence I am hesitant to pull the trigger on anything yet.

                 

                I want to build an optimal subsystem for these cards to flourish. I don't build to upgrade next year!

                 

                Cheers

                  • Re: CFX Fury X PCI-E lane requirements
                    ucouldbrong

                    Don't believe everything people post on here just because...they can.

                      • Re: CFX Fury X PCI-E lane requirements
                        n4cr

                        Definitely. I can't trust much at this stage other than AMD or a rigid testing method. So 5820 vs 5930 back to back, on a Fury-X CFX rig, or forcing PCI-E modes with a 59xx cpu.

                         

                        I have a very sneaking feeling AMD might not answer this one, to avoid possible negative press e.g. 'you need a full on set up to max a Fury X in CFX'. But if the benefits are anything like what is shown in the 980Ti video, then it's well worth it to build a system like that.

                      • Re: CFX Fury X PCI-E lane requirements
                        Thanny

                        You might want to look here.  They're using an nVidia 980 for testing, but I would expect the results with AMD hardware to be much the same.

                         

                        In short, PCIe throughput matters hardly at all for most games, but quite a bit for some.  In general, the newer the game, the more likely it needs to get data back from the GPU to the CPU for post processing, and therefore the more impact a slower bus will have on it.

                         

                        If it's a matter of choosing your chipset, I would certainly not recommend one that limits you to 16 total lanes.  Either go with the better socket (2011), or get a board with a PLX chip.  I'd personally go for the former, because just adding extra lanes for a second GPU isn't going to cut it for my needs.  I have other peripherals that need their own lanes, which is why I went with a Sandy Bridge-E CPU a couple years back.

                          • Re: CFX Fury X PCI-E lane requirements
                            n4cr

                            Thank you, have seen that article but it's not an HBM card, or dual setup, so I can't draw so much from it. Specifically the no crossfire bridge approach and pooled memory setup on the Fury has me wondering.

                             

                            Hadn't considered a PLX chip, will dig further down that avenue, although as you rightly point out, more lanes not just for GPU-GPU is useful, let alone with the Fury approach GPU-RAM-GPU possibly being a bit more demanding on those lanes.

                      • Re: CFX Fury X PCI-E lane requirements
                        flano

                        I'm using FURY X CrossFire on a Z87X-UD5H I'm pretty sure one is 16x and the other is 8x lane? works fine, and one card is SAPPHIRE, while the other is a GIGABYTE (both AMD reference designs? so basically identical? somebody chime in!!) checked with GPU-Z and one has the early CM waterpump and the 2nd has the revised one! each obviously have different bios/firmware but run fine together!!

                          • Re: CFX Fury X PCI-E lane requirements
                            n4cr

                            Yes, reference designs are the same, (other than pump revision), made to AMD spec. I always aim for reference designs because the OC community usually bases on this, plus being first, there is no speed binning for these early cards, as the e.g. 'FURY X MAXX TOPP GOLDEN CROWN EDITION 999' has not been released, with a factory OC, which would require validation and testing of stock to ensure OCs are reached, to avoid RMAs. This can lead to non OC edition cards being poorer overclockers, if the entire product line is tested.

                             

                            Do you notice any noise difference between the pumps? Or any noise resonation between the two cards at particular RPMs?

                            When did you purchase each one?

                             

                            And yes you will be running 16/8x.

                              • Re: CFX Fury X PCI-E lane requirements
                                flano

                                I purchased 2x Sapphire R9 FURY X from a computer parts orientated website but there was only 1 card left in stock, they messed me around a bit on the 2nd card. Stock came in and was showing as Available on the website and I had a pending order and I wasn't allocated stock!!!

                                 

                                Ended up waiting so long I decided to cancel the order from this particulaur website.

                                 

                                Just the sapphire card has a waterpump whine noise, the revised GIGABYTE card is dead silent.

                                 

                                I mounted both radiators at the top of the case, pulling air from above the CPU and up out of the case, I'm sure this isn't a great method but it seems to work fine.

                                 

                                The pump whine is there but nothing I cant live with if you had a completely silent system and this pump noise was the only thing making noise it would be probably be a pest and quite annoying but overall I'm not phased by it.

                                 

                                The Sapphire card was purchased 29/06/2015 and the GIGABYTE I bought just recently was 21/07/2015.

                            • Re: CFX Fury X PCI-E lane requirements
                              amdmatt

                              You will have no issues running 2x Fury X on either X16 or X8 PCI-E 3.0 lanes. In addition, you will be fine using X16 or X8 PCI-E 2.0 lanes. More bandwidth is of course always better, but the differences are still small.

                               

                              If you're going to be gaming at 4K or higher, then X8 PCI-E 3.0 - X16 PCI-E 2.0 as a minimum makes sense, otherwise you'll be fine with PCI-E 2.0 X8.

                               

                              Sorry for the late reply on this thread chaps, the forum has exploded recently with activity.

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