DX12 Multi-GPU Details?

Discussion in 'Rendering Technology and APIs' started by swaaye, Jun 1, 2016.

  1. swaaye

    swaaye Entirely Suboptimal
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    Does multi GPU have the frame latency problems of CF and SLI?
     
  2. MDolenc

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    Are you aiming at explicit multi GPU in DX12? It depends entirely on the game implementation. If game is doing AFR then obviously yes. If it's doing something else then not necessarily.
     
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  3. TomRL

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    Would buying two 480's for crossfire be a reliable way of getting 1080 levels of performance in DX12? I've heard that DX12 natively does crossfire but I haven't looked in to how reliable it is. I want 1080 levels of performance in DX12 but also want the more future-proof Async in AMD gpu's.
     
  4. swaaye

    swaaye Entirely Suboptimal
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    If your favorite game with mGPU uses AFR, then your dualie midrange setup that benches like a 1080 isn't going to actually play like a 1080. And yeah....hoping that both the IHV and game company make multi-GPU work is historically not a pretty thing.
     
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  5. Kaotik

    Kaotik Drunk Member
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    No. DX12 doesn't support CF or SLI at all, instead it has new multiGPU-modes one of which allow mix'n'matching even different vendors. However, multiGPU-support is now solely in the hands of game developers, they have to implement to support for it to work, not AMD or NVIDIA.
     
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  6. Infinisearch

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    Actually DX12 supports implicit multi-GPU which is classic driver controlled SLI/CF.
     
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  7. Kaotik

    Kaotik Drunk Member
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    To my understanding it still requires the developers specifically implementing that support for their game, instead of AMD/NVIDIA driver magics?
     
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  8. Razor1

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    Yes its pretty much the same as before. Developers still have to tailor their games for mGPU just the same way as SLi and Xfire, the benefit is only now you can have multiple IHV cards.
     
  9. Infinisearch

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    I have to look for it but there was a presentation that described all the multi GPU "modes" of DX12. However read the first sentence of this page. https://msdn.microsoft.com/en-us/library/windows/desktop/dn933253(v=vs.85).aspx and you will see it mentions a case where drivers handle using multiple gpu's.
     
  10. Razor1

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    two modes explicit and implicit, explicit gives developers complete control, implicit minimal work to get it work but still that depends on how the engine is made to begin with.
     
  11. Infinisearch

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    I know, I mentioned implicit above.
     
  12. Alessio1989

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  13. Kaotik

    Kaotik Drunk Member
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    Maybe I'm mistaken, but IIRC AMD/NVIDIA could implement CF/SLI on games on older APIs regardless of developer effort (of course in recent times the game engines have become more and more incompatible with "brute force AFR" due inter-frame data used and whatnot, but given that there's not specifically anything preventing it in the engine, it could be done?)
     
  14. Razor1

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    Yes older API's its not a problem. In dx12 there is no support for SLi or Xfire
     
  15. Kaotik

    Kaotik Drunk Member
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    Which was my point to begin with "even though there's still similar mode, it's not the same"
     
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  16. Alessio1989

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    SLI and CFX are just the commercial names for linked-adaptor mode. Linked adaptors are supported under D3D12. What is not supported is the "driver magic" which force AFR. Everything must be handled by the application.
     
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