When Nvidia Support Combining VRAM in Windows 10 DX-12?

Discussion in 'Videocards - NVIDIA GeForce' started by zeebaluch, Sep 14, 2015.

  1. zeebaluch

    zeebaluch Member Guru

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    I have heard that Windows 10 DX-12 supports combining VRAM and Mix GPU's as well. As you all know Windows 10 has been launched couple of months ago, so when it'll be possible that if we SLI/Crossfire our GPU's to take their combine VRAM advantage like 4x4=8GB? Any comments regarding this knowledge would be helpful for all of us.
     
  2. Thalyn

    Thalyn Member Guru

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    It's got nothing at all to do with the vendor and everything to do with the developers. Because of how DX12 resource allocation has to be done (eg You need to tell it which card and where you're trying to place whatever information in, which card draws what, etc) it doesn't matter what mixture of cards or how many of them you have. Heck, if they really wanted to than it would be possible (daft, but possible) to link a discrete GPU to an on-die GPU.

    So you'll be able to take advantage of it when DX12 titles surface that actually support it.

    It was never some kind of magic which allowed all titles to suddenly pool the VRAM regardless of the title or its APIs, just so long as you're running Win10. It's always been something that had to be specifically programmed for on a title-by-title (or at least engine-by-engine) basis which also requires that you be running Win10.
     
  3. Nono06

    Nono06 Master Guru

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    +1. In addition, for video games this will be more or less useless. The links between the 2 GPUs are too slow to quickly exchange huge amount of data.
    So having 4GB+4GB will never be equivalent to 8GB.
    If the second card also works on texturing, it requires having the textures in its VRAM.
    One thing possible with DX12 is having an asymmetric configuration: a master card with a lot of VRAM and a second or third GPU with less memory just for geometry, physics or any other compute task. Texturing will be done by master card with all the data in its VRAM.

    I fully agree with zeebaluch, too many people think that DX12 will change things magically. It is not the case and current HW implementation has also to be entirely rethink to take advantage of all DX12 features.
     
    Last edited: Sep 14, 2015
  4. fantaskarsef

    fantaskarsef Ancient Guru

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    This won't bring any real gains even if they'd put it in. Before any of this will make sense, GPUs will become way faster, making any improvements on the PCIe just too slow again.

    It's a nice idea, even if they just implement SFR, but I don't think it will see much use in the next years. You also could look at it that way: there's already games where SLI or CFX is broken at launch, then sometime down the road it works more or less... will be the same, or even worse if the devs are asked to implement such low lever access for two cards after launch.
     

  5. Nono06

    Nono06 Master Guru

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    With Dx12 devs will have more flexibility, therefore other technics for rendering frames in multi GPU context can be considered rather than AFR or SFR.
    For example, UE4 is not by default meant to be used in MultiGPU because of inter-frame dependencies (see "A boy and his Kite" demo).
    We can imagine that only some tasks in a frame depends on a previous one. In DX12, dev have normally more granularity and can decide to execute those tasks always on the same GPU and the rest where you have resources available. One card at the end gather all the data and build the final image. So throughput could increase but as already seen in Ashes DX12 benchmark latency also.
     
    Last edited: Sep 14, 2015
  6. fantaskarsef

    fantaskarsef Ancient Guru

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    With today's devs and the pc porting that lets you wish for anything better but what you get, I seriously doubt that any non pc-exclusive titel will seriously be optimized by the devs. Games these days are NOT programmed to work good on PC, but to run at 30fps on consoles. So I'm not very optimistic we will see lots of super coded games that make 99%+ use of our hardware.
     
  7. southamptonfc

    southamptonfc Ancient Guru

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    Unfortunately this is the truth. Back in the (good?) old 8bit days, programmers would be drooling over the possibility of being able to maybe use an otherwise unused CPU IGP to do some extra number crunching on the side.
     
  8. nhlkoho

    nhlkoho Ancient Guru

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    There could be so many possible combinations of GPU's in the system that I can see it being completely worthless for any dev to even try to implement it. It's a nice idea in theory, but in reality it won't work well.
     
  9. Nono06

    Nono06 Master Guru

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    100% agree with your comments.

    I may be even more pessimistic. Dev have such control on HW that it could ends with even less optimized game than before.

    PC eco-system strength is also its weakness. There are so many possibilities in HW configuration that for me, it will be impossible to make games works properly in every situation unless being really conservative. And since optimization in driver will have less impacts, we will have situation where DX12 will bring no performance if not a degradation.
    It is too early to consider Ashes test as a good exemple but....
     
  10. CK the Greek

    CK the Greek Maha Guru

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    Well,ok many games released un-optimised and some patches did their work however there are few companies who try and make their released games optimised from day one. Examples the two last titles who all of us know, MGS 5 and Mad Max. There are few (comparing to thousands other) users who still have some issues but usually it's lack of some s/w components or unstable oc. No one can argue about these two titles.


    Don't judge now Win 10 and dx12, it's WAY too early, no matter if you like it or not,this is the truth..
     

  11. fantaskarsef

    fantaskarsef Ancient Guru

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    I'm not trying to judge win10 or dx12, but I'm thinking about the optimizations and how often we will see them for anything beyond standard compatability.
     

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