Time Spy and Crossfire

Discussion in 'Videocards - AMD Radeon Drivers Section' started by THEAST, Jul 15, 2016.

  1. Cave Waverider

    Cave Waverider Ancient Guru

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    As I understand it, it isn't a bug, it's the way the benchmark is coded. AMD can't really do anything about it, as DX12 Multi GPU support is to be implemented with the software and drivers have little control over DX12 compared to earlier DirectX versions. There are various ways to do this and it's up to the software manufacturer whether they code in support for non-matching cards or not. In this instance, they chose not to.
     
    Last edited: Jul 19, 2016
  2. THEAST

    THEAST Master Guru

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    3DMark's devs say the opposite; they say their benchmark queries the number of GPUs from the driver and they will use any number of GPUs the driver makes available. In this case, AMD's driver is only making one GPU available to the benchmark.

    Time Spy uses Linked-node Multi-Adapter that uses the existing SLI/CF interface made available by the driver. AotS, on the other hand, uses Multi-node Multi-Adapter which gives explicit control over each individual GPU, without interference from the driver, which is also the reason why CF/SLI has to be disabled in the driver for multi-GPU to work in AotS. The former case is much easier to implement, but doesn't seem to work with non-identical GPUs. The latter is harder to implement but will even work with mixed-NVIDIA-AMD cards.

    Needless to say, judging by the amount of optimization that is going into games these days (or lack of it, for that matter), we should probably expect most DX12 games to support multi-GPU only in Linked-node mode; of course that is if they bother to even support multi-GPU and/or DX12 in the first place.
     
  3. albertfu

    albertfu Member

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    Crimson 16.7.2 is now WHQL certified, will see if it changes anything.
     
  4. holler

    holler Master Guru

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    https://blogs.msdn.microsoft.com/di...rectx-12-multigpu-and-a-peek-into-the-future/


    here is an interesting blog from Microsoft on the future of multi-gpu in DX12. pretty interesting read. I think these moves will make it easier for developers to embrace multi-gpu in DX12 and beyond instead of relying on a combination of GPU vendor driver implementations and game developers as much.
     

  5. mtrai

    mtrai Maha Guru

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    Well I can say that a R9 290 and R9 390 work in Time Spy in Crossfire, just received my R9 290X back from RMA a bit ago and got an R9 390 not sure if I should be happy or not lol. I know the 290 and 390 are technically the same but thought I would add.
     
  6. THEAST

    THEAST Master Guru

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    Thank you for the link. Though there is also some bad news:

    In other words, RotTR is also using Linked-node mode which means CF for none-identical cards is probably not going to work in this game either; ouch...

    Hmm, that is interesting. R9 290 and 390, despite using the same GPU, certainly don't perform identically due to different core and memory clocks, but the driver seems to be considering them as similar-enough in this case. At least you can have working DX12 CF with the 290 and 390; something you cannot have with 290 and 290X right now, which is ridicules.
     
  7. mtrai

    mtrai Maha Guru

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    I did a little, only a little investigation last night as I am in the middle of moving, but in TimeSpy it seems to see both cards as a 390. I checked in AOTS as well in both Xfire and Explicit multi adaptor and it also sees both cards as a 390.

    Not really gonna have to time to check this out until the weekend.

    Should I be happy or upset that they replaced my 290X with a non x 390? (it seems to run better then my old 290X but not really had time to test it)
     
  8. THEAST

    THEAST Master Guru

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    390 and 290X use the same chip, so IPC (Instruction per Clock) is the same. They also have roughly the same GPU clock, but 290X has 256 more shaders which will translate to ~10% better compute performance on 290X. On the other hand, 290X uses 5 GHz memory, while 390 uses 6 GHz, that would translate to quite a bit higher memory bandwidth on 390, but only around 5-6% better gaming performance. In total, 290X is probably 1-2% faster than 390; 3DMark's result databases also suggest a similar difference, which is negligible in my opinion.

    Considering this, in games that CF works, 290 + 290X would probably give you 1-2% better performance compared to 290 + 390, but, as we have been discussing here, 290 + 290X will not work in DX12 Linked-node mode, while 290 + 390 seems to work. If AMD never fixes this issue, you have won big time by getting back a 390 instead of 290X, since most upcoming DX12 titles will probably use Linked-node mode for CF, and even if AMD fixes it, you might lose 2-3 FPS compared to your previous setup, but still got a newer card which will probably last longer, too. Right now, I think you should be happy.
     
    Last edited: Jul 21, 2016
  9. mtrai

    mtrai Maha Guru

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    @TheEast thanks that put it in perspective for me, not had much time to mess around and test since I am in the middle of moving. I only get to sit down when I am eating or needing a break lol.
     
  10. THEAST

    THEAST Master Guru

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    I feel your pain, moving isn't something anybody would ever look forward to. Good luck.
     

  11. THEAST

    THEAST Master Guru

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    For people who are interested, I just tested Rise of the Tomb Raider on my non-symmetrical CF setup. As I expected, just like Time Spy, CF does not work in RotTR DX12 mode either, while it works just fine in DX11 mode. I am not sure whether I should blame myself for adding a 7970 instead of a 7950 to my setup, or blame AMD for failing to support my setup in CF for DX12, despite the fact that it is supported on DX11...
     
  12. PrMinisterGR

    PrMinisterGR Ancient Guru

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    CFX works in Tomb Raider DX12, if you have it enabled from Crimson. Unless it doesn't work for GCN 1.0, which I somehow don't think so.
     
  13. THEAST

    THEAST Master Guru

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    The problem is with CF setups with non-identical cards. 7950 + 7950 and 7970 + 7970 works just fine in both DX11 and DX12, while 7950 + 7970 (and 280 + 280X, 290 + 290X, etc.) only work in DX11 and not in DX12. Apparently AMD cannot be bothered supporting such configurations in Linked-node Multi-adapter. Of course my setup works in AotS, but that uses Multi-node Multi-adapter and completely bypasses the driver.
     
  14. pakoo

    pakoo Member Guru

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    Same problem here. 295x2 + 290x :(. When Will fix AMD??
     
  15. THEAST

    THEAST Master Guru

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    In your case if you remove the 290X from your machine, or disable it from TriFire and just have the two GPUs on the 295x2 running in CrossFire, it should work with DX12; have you ever tried this?

    You can report this issue if you want, I have done it multiple times, but AMD is not going to fix this because it only affects a very small minority of users.
     

  16. Chastity

    Chastity Ancient Guru

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    Wouldn't it be better to report it to 3DMark, as the onus for mgpu support in DX12 is on the developer, not AMD.
     
  17. THEAST

    THEAST Master Guru

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    This problem is not limited to 3DMark, it applies to every game and app that uses Linked-node Multi-adapter (i.e. every game with DX12 multi-GPU support except AotS). I have already reported this in 3DMark's forum; they put the blame on AMD's driver. Please check the previous replies for more info.
     
  18. Alessio1989

    Alessio1989 Ancient Guru

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    If even the simple Microsoft samples for linked-adapters do not work on those configuration, you should all report this as a driver bug to AMD (running AMD Problem Report Wizard).
    I am also not aware about any D3D12 technical limitation involving this.
     
  19. THEAST

    THEAST Master Guru

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    Believe me, I have done it multiple times. I created this thread 7 months ago, I have reported this issue to AMD at least three times since then, they simple don't care. They could easily just say Linked-node mode is only for 100% identical GPUs and the fact that they do support CF for non-symmetric setups in DX11 is just a courtesy from AMD which is not going to be repeated for DX12. Even if I was in their management team, I would probably not spend any manpower fixing such an issue that affects such a small minority of users.
     
  20. yasamoka

    yasamoka Ancient Guru

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    In that same game, RotTR, I have working CF in DX12 mode on my 290X CF setup and I've played most of the game using that mode (when I discovered that DX12 worked better than DX11 with framerates and smoothness) till the finish.
     

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