AMD Ends Crossfire For More Than 2 GPUs – Now Calls It mGPU

Discussion in 'Frontpage news' started by Hilbert Hagedoorn, Sep 25, 2017.

  1. Hilbert Hagedoorn

    Hilbert Hagedoorn Don Vito Corleone Staff Member

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  2. KissSh0t

    KissSh0t Ancient Guru

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    Maybe they are stopping use of the word fire for a reason.

    That.... that's the joke.

    I will let myself out.
     
    Last edited: Sep 25, 2017
  3. AlbertX

    AlbertX New Member

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    I still don't understand this Multigpu is Dying scenario.

    I Understand it makes no sense to give official support for 3 or 4 cards because the way SLI or CF works at the moment is very complicated to optimize, and this way Nvidia and AMD will just not have to provide support.

    But to me 2 cards are more alive than ever, not only FOR MY MONEY, 2 1070 or 1080 works beautiful, but they have lower latency, frame time than years ago. And I tested more than 40 games and 36 of them worked, only 4 games didn't.

    The Scalibility has also improved a LOT, I get no less than 70% and on the majority of games I get around 85% some games I got around 95% and in ONE game, no Idea why I got exactly 100% scalability (the game is Sleeping Dogs).

    Anyway, I still Think SLI or CF will be alive and is one of the best way to play some games.
     
  4. fantaskarsef

    fantaskarsef Ancient Guru

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    Marketing. First of all they're just getting rid of the name (in this announcement), maybe they try to push people buying the top card more often than just buying two lower tier cards.
    But fact is, in terms of display technology we're a bit ahead of what single GPUs are able to provide, so to drive some displays to their fullest potential, you currently need to have two GPUs running.

    Don't get me wrong, I wasn't "suffering" from 980 SLI, but eventually it's a lot easier and less of a hassle to run a single gpu tbh, no more worrying when this SLI bug will be fixed or that game finally gets mGPU support.
     

  5. SL4T

    SL4T Member

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    I believe they are moving towards multi-core GPUs kinda like the direction CPUs had to go eventually when they started hitting frequency ceilings.
     
  6. rl66

    rl66 Maha Guru

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    Since mGPU is supported by DX12 out of the box (also in mixed AMD/NVidia) then SLI and Xfire will slowly become obsolete,
    even more now that a single card can handle screen resolution that were impossible with single card few years ago.

    Also 2 GPU is enough don't you think?

    i was loving SLI but yes, now if i would build a system for gaming it would be single GPU.
     
  7. AlbertX

    AlbertX New Member

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    With SLI or CF all I meant is more than 1 GPU.

    For me to go to 1 GPU it needs to be more cost efficient than 2 Lower GPU in SLI, at the time 2 1070 made more sense in terms of money than 1 Titan XP or similiar cards.
     
  8. fantaskarsef

    fantaskarsef Ancient Guru

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    Just a quick question, does anybody have some oversight on what games in dx12 modes really do support mGPU yet? I am not following that anymore.
     
  9. OddGentleman

    OddGentleman New Member

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    An AMD rep said, "CrossFire isn’t mentioned because it technically refers to DX11 applications. In DirectX 12, we reference multi-GPU as applications must support mGPU, whereas AMD has to create the profiles for DX11. We’ve accordingly moved away from using the CrossFire tag for multi-GPU gaming."

    The driver software team no longer have to optimize each multi-GPU profile to work on games. DirectX12 has a feature called ‘Explicit Multiadapter’ which puts that burden on the game developer.

    This feature not only makes the traditional similar GPU-type CrossFire or SLI possible, but it also allows different GPUs to work together. This even includes cross-manufacturer mGPU such as AMD + NVIDIA to work together. Ryan Smith from Anandtech actually wrote an article demonstrating this as far back as 2015.

    DirectX 12 brings the ability to combine memory pools, provided the game developer creates their games with this feature in mind.

    In traditional AFR based Multi GPU rendering, both GPUs are working on separate frames of the same scene, requiring both GPUs to hold exactly the same data in each GPUs VRAM as both are working on the same tasks. Without explicit mechanisms to utilize multiple GPUs, tasks cannot be decided in such a way that the GPUs could do different enough tasks to utilize their memory pools separately.

    With DirectX 12 developers can specifically allocate tasks to a specific GPU, allowing them to control the GPU hardware in such a way that each GPU could use their full frame buffer independently, meaning that 2 4GB cards in SLI or Crossfire could create a setup with 8GB of effective GPU memory.
     
  10. fantaskarsef

    fantaskarsef Ancient Guru

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    Yeah we all know and have seen how dx12 actually supports mGPU systems natively only that the games don't, do they?
     

  11. JonasBeckman

    JonasBeckman Ancient Guru

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    DirectX 12 and Vulkan support multi-GPU within the API whereas from my understanding DirectX 11 (And earlier.) do not, thus why you needed driver profiles that try to work around this limitation.
    https://www.reddit.com/r/Amd/comments/727stb/amd_drops_support_for_3_4way_crossfire/

    DX12 and VLK are however dependent on the developers using and implementing these features in a good way which is likely why some of the current initial games for these API's had poor or otherwise very limited support for multi-GPU configurations to where it was patched in weeks or months post-release which is a really poor scenario, what with time and skill requirements to implement Crossfire and/or SLI I'm expecting it would be almost required for AMD or Nvidia to have hands-on support for the game in question and in Nvidia's case they seem to favor a DX11 implementation.

    A few more years for both DirectX 12 and Vulkan to mature a bit and more developers to give these API's a try and slowly learn and become familiar with them might see the situation improve, have some doubts as to whether mixed-GPU mode will ever see any notable use though although some game might have support for it. (Ashes of Singularity is still the only one that does?)

    DX11 isn't going anywhere either as MS supports both in tandem too so DirectX 12 adaption might be slow with developers already being very familiar with D3D11 though AMD might try to push for the API getting some use in some games they're supporting directly.

    No clue as how Vulkan will go, seems OpenGL is also still supported but for Windows DirectX is the more popular API by far although with VLK not being limited to Win10 it might see some use although I wouldn't be surprised if the shift also takes a few years.
    (Not too sure as to when version 1.1 is planned either, current SDK should be somewhere around version 1.0.6.1 implementing bug fixes and requested extensions but there's very few games actively using the API though applications and software such as emulators have had some benefits from it too.)
     
  12. asturur

    asturur Active Member

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    If mGpu, SLI would automatically scale at 200% performance in every game, that would be bad for card market.

    When a new card comes out, is easier/cheaper to buy one as you have and double your perf up rather then switching to the new one.

    I m not a big gamer, i do not update my computer since long, but when i was doing i was always on SLI and i loved it.
     
  13. sammarbella

    sammarbella Ancient Guru

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    Really? Game devs don't know that. :D

    If this was true ALL DX12 should have mGPU support but that's not the case.

    Some "optimized" Windows games like Quantum Break (DX12 version) could use mGPU but devs said:

    https://www.bit-tech.net/news/gaming/pc/quantum-break-no-multi-gpu/1/

    mGPU is a possibility in DX12 BUT it needs more work (A LOT) from game devs than in old DX11.
    In fact in DX12 ALL the NEEDED work to support multi GPU in games must be done exclusively by game devs and NONE by GPU makers.

    Yes.

    It was done once in the AMD showcase called AOTS

    No more "practical cases".

    Right now mantle had more success than DX12 mGPU.

    LOL
     
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  14. RzrTrek

    RzrTrek Maha Guru

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    It only takes one AMD graphics card to fry an egg.
     
  15. Kaarme

    Kaarme Master Guru

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    I thought you guys used electric stoves in Sweden, but perhaps you live in an old urban apartment with gas? Typically electric stoves use 1.5-2kW of power. AMD video cards fall short by far.
     

  16. vbetts

    vbetts Don Vincenzo Staff Member

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    Dinner and entertainment.
     
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  17. geogan

    geogan Master Guru

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    There has already been thousands of cores in a GPU die for years... you must mean multiple dies... ie multiple GPUs on a single card.. also done years ago.
     
  18. schmidtbag

    schmidtbag Ancient Guru

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    You're right - multi-GPU isn't dying. What's dying are the methods used. SLi and CF are horribly messy, inefficient, and outdated. Depending on your workload, having more than 2x just isn't worth it for most people. But we're reaching a point where software or hardware bridges between GPUs isn't necessary anymore. Take a look at how servers, grid computing, render farms, and at-home OpenCL/CUDA tasks work. You don't even need an active display in order to use your "peripheral" GPUs. I forget if DX12 supports this, but Vulkan also supports platform-agnostic multi-GPU. In other words a Vulkan application can (doesn't mean will) be designed to utilize whatever GPUs are available. This to me is fantastic, because it could even put use to IGPs.

    The sad realization to me is we're now finally at a point where we can do 3x or 4x GPUs in CF/SLi without any loss in performance due to bandwidth.

    For me personally, I once had a CF setup and unlike most people, I didn't find it that miserable of an experience. Most troubles I had could easily be fixed with some minor CCC adjustments. However, I'm not sure if I would do it again (largely because my current chassis is an ITX, but, I also went for ITX because I had no intention on multi-GPU). But, that doesn't mean I'm abandoning it - I have a BOINC rig with 4x GPUs in it, Nvidia and AMD mixed. Well, technically 3, I had to remove one because the PSU will otherwise get over-loaded.
     
  19. geogan

    geogan Master Guru

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    Anyone know what the current situation is with multiple GPUs being used for VR on for example Oculus? Does Oculus have to implement it or developers or NVidia? I think even the latest AAA VR games like Project Cars 2 doesn't even support one-GPU-per-eye yet which is a massive PITA...o_O
     
  20. schmidtbag

    schmidtbag Ancient Guru

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    To answer your question, neither the HMD nor GPU manufacturers are responsible; it is up to the game developers. I forget if Nvidia's control panel lets you do it, but AMD allows you to force-enable Crossfire on applications that don't support it. It doesn't scale perfectly but you'll get at least some performance boost.

    Regardless, unless you're totally immune to motion sickness, I would avoid multi-GPU with VR like the plague. Multi-GPU is what you do when you're struggling to reach 60FPS at max detail, whether that's because you've got some crazy screen resolution, a game designed way ahead of its time, or because you bought a mid-range GPU that isn't keeping up. You sacrifice latency for more FPS, and when it comes to VR, every millisecond delay counts.
     

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