Exclusive: DirectX 12 Will Allow Multi-GPU Between GeForce And Radeon

Discussion in 'Frontpage news' started by pbvider, Feb 24, 2015.

  1. pbvider

    pbvider Master Guru

    Messages:
    989
    Likes Received:
    0
    GPU:
    GTX
    " We have early information about some of the details regarding DirectX 12, and what follows will surprise you.

    A source with knowledge of the matter gave us some early information about an "unspoken API," which we strongly infer is DirectX 12.

    We first heard of DirectX 12 in 2013, and DirectX 12 appears to finally be around the corner. It's expected to launch in tandem with the upcoming Windows 10 operating system.

    The new API will work much differently from older APIs, and it's common knowledge by now that it will be "closer to the hardware" than older APIs, similar to AMD's Mantle. This will bring massive improvements in framerates and latency, but that's not all that DirectX 12 has up its sleeve.
    Explicit Asynchronous Multi-GPU Capabilities

    One of the big things that we will be seeing is DirectX 12's Explicit Asynchronous Multi-GPU capabilities. What this means is that the API combines all the different graphics resources in a system and puts them all into one "bucket." It is then left to the game developer to divide the workload up however they see fit, letting different hardware take care of different tasks.

    Part of this new feature set that aids multi-GPU configurations is that the frame buffers (GPU memory) won't necessarily need to be mirrored anymore. In older APIs, in order to benefit from multiple GPUs, you'd have the two work together, each one rendering an alternate frame (AFR). This required both to have all of the texture and geometry data in their frame buffers, meaning that despite having two cards with 4 GB of memory, you'd still only have a 4 GB frame buffer.

    DirectX 12 will remove the 4 + 4 = 4 idea and will work with a new frame rendering method called SFR, which stands for Split Frame Rendering. Developers will be able to manually, or automatically, divide the texture and geometry data between the GPUs, and all of the GPUs can then work together to work on each frame. Each GPU will then work on a specific portion of the screen, with the number of portions being equivalent to the number of GPUs installed.

    Our source suggested that this technology will significantly reduce latency, and the explanation is simple. With AFR, a number of frames need to be in queue in order to deliver a smooth experience, but what this means is that the image on screen will always be about 4-5 frames behind the user's input actions.

    This might deliver a very high framerate, but the latency will still make the game feel much less responsive. With SFR, however, the queue depth is always just one, or arguably even less, as each GPU is working on a different part of the screen. As the queue depth goes down, the framerate should also go up due to freed-up resources.

    The source said that with binding the multiple GPUs together, DirectX 12 treats the entire graphics subsystem as a single, more powerful graphics card. Thus, users get the robustness of a running a single GPU, but with multiple graphics cards.

    It should be noted that although the new Civilization: Beyond Earth title runs on Mantle, it has an SFR option and works in a similar way because AMD's Mantle API supports SFR. Mind you, Split Frame Rendering is not a new trick by any means. Many industrial film, photography, and 3D modelling applications use it, and back in the 90s some game engines also supported it.

    Of course, chances are you won't be able to use all of the options described above at the same time. Split frame rendering, for example, will still likely require some of the textures and geometry data to be in multiple frame buffers, and there may be other sacrifices that have to be made.

    Build A Multi-GPU System With Both AMD And Nvidia Cards

    We were also told that DirectX 12 will support all of this across multiple GPU architectures, simultaneously. What this means is that Nvidia GeForce GPUs will be able to work in tandem with AMD Radeon GPUs to render the same game – the same frame, even.

    This is especially interesting as it allows you to leverage the technology benefits of both of these hardware platforms if you wish to do so. If you like Nvidia's GeForce Experience software and 3D Vision, but you want to use AMD's TrueAudio and FreeSync, chances are you'll be able to do that when DirectX 12 comes around. What will likely happen is that one card will operate as the master card, while the other will be used for additional power.

    What we're seeing here is that DirectX 12 is capable of aggregating graphics resources, be that compute or memory, in the most efficient way possible. Don't forget, however, that this isn't only beneficial for systems with multiple discrete desktop GPUs. Laptops with dual-graphics solutions, or systems running an APU and a GPU will be able to benefit too. DirectX 12's aggregation will allow GPUs to work together that today would be completely mismatched, possibly making technologies like SLI and CrossFire obsolete in the future.

    There is a catch, however. Lots of the optimization work for the spreading of workloads is left to the developers – the game studios. The same went for older APIs, though, and DirectX 12 is intended to be much friendlier. For advanced uses it may be a bit tricky, but according to the source, implementing the SFR should be a relatively simple and painless process for most developers.

    Queueing frames has been a difficult point for various studios, such that on some games SLI or CrossFire configurations don't even work. The aggregation together with SFR should solve that issue.

    That's as far as we can reach into the cookie jar for now, but we expect to see and learn more at GDC."

    Source: Tom`s Hardware
     
  2. nhlkoho

    nhlkoho Ancient Guru

    Messages:
    7,752
    Likes Received:
    362
    GPU:
    RTX 2080ti FE
    I'll believe it when I see it. SLI and Crossfire don't work half the time currently so I have no faith in this being any better. I also imagine that this will be a nightmare when it comes to working drivers.
     
  3. Fox2232

    Fox2232 Ancient Guru

    Messages:
    11,809
    Likes Received:
    3,366
    GPU:
    6900XT+AW@240Hz
    Will work same way as PhysX works in combined systems.
     
  4. GreenAlien

    GreenAlien Active Member

    Messages:
    63
    Likes Received:
    5
    GPU:
    Sapphire Nitro+ RX 480 OC
    More interesting than AMD/Nividia would be Intel/AMD, Intel/Nvidia, because most people with a dedicated gpu have an unused Intel one..
     

  5. HeavyHemi

    HeavyHemi Ancient Guru

    Messages:
    6,954
    Likes Received:
    959
    GPU:
    GTX1080Ti
    Claiming SFR is a 'new frame rendering method' makes you wonder about the accuracy of the rest of the article.
     
  6. sykozis

    sykozis Ancient Guru

    Messages:
    22,012
    Likes Received:
    1,201
    GPU:
    MSI RX5700
    SFR.... Lucid Hydra comes to mind here..... SFR is what Lucid's Hydra used. Hydra also claimed to allow AMD and NVidia graphics cards to work together. This article makes it sound like Lucid is involved in the development of DX12.....
     
  7. CalculuS

    CalculuS Ancient Guru

    Messages:
    3,075
    Likes Received:
    295
    GPU:
    GTX 1660Ti
    Last edited: Feb 24, 2015
  8. nhlkoho

    nhlkoho Ancient Guru

    Messages:
    7,752
    Likes Received:
    362
    GPU:
    RTX 2080ti FE
    Maybe they meant a new way of implementing it or something.

    Near the bottom they say
     
  9. HeavyHemi

    HeavyHemi Ancient Guru

    Messages:
    6,954
    Likes Received:
    959
    GPU:
    GTX1080Ti
    Back in 2005 along with SFR and AFR, was Supertiling from ATI.
     
  10. Veteran

    Veteran Ancient Guru

    Messages:
    12,103
    Likes Received:
    21
    GPU:
    2xTitan XM@1590Mhz-CH20
    Even if it did work there is no way i will put an AMD card in my machine, not a chance even if it was for free.:)
     

  11. ---TK---

    ---TK--- Ancient Guru

    Messages:
    22,110
    Likes Received:
    2
    GPU:
    2x 980Ti Gaming 1430/7296
    For free I would give it a go no problem.:) Thats the extent of my budget for this experiment. $0.
     
  12. Rich_Guy

    Rich_Guy Ancient Guru

    Messages:
    12,708
    Likes Received:
    676
    GPU:
    MSI 2070S X-Trio
    Nvidia won't allow it.
     
  13. zer0_c0ol

    zer0_c0ol Ancient Guru

    Messages:
    2,976
    Likes Received:
    0
    GPU:
    FuryX cf
    say the man who has one of the worst nvidia card in his setup.. judging by the signature

    oh the irony
     
  14. thatguy91

    thatguy91 Ancient Guru

    Messages:
    6,643
    Likes Received:
    99
    GPU:
    XFX RX 480 RS 4 GB
    I remember seeing a few months ago AMD were working on this to combine the APU with a dedicated AMD video card. It's probably just an extension of the DirectX SFR in that it does the same thing, but in a more efficient way?

    It could also be that they're developing it for use with DirectX 11.3 etc, which is being released alongside DirectX 12. A year after Windows 10 comes out there is no excuse for gaming companies to release games that aren't DirectX 11.3 or 12 (in effect, Windows 10 exclusives). Since Windows 10 is a free upgrade for Windows 7 and 8.1 users, using compatibility as an excuse is just a poor excuse for bad ports or lazy development. Even at 6 months, this would be true!

    Not all games will be DirectX 12 though, it will be interesting to see how many will be DirectX 12 and how many will be DirectX 11.3. Games that are DirectX 12, even the early ones, will unlikely to support other DirectX versions, seeing as it would involve a considerable amount of extra work to support DirectX 12 and older DirectX revisions. If they do, it will most likely mean DirectX 12 won't be fully utilised or optimised.
     
  15. Denial

    Denial Ancient Guru

    Messages:
    13,563
    Likes Received:
    3,117
    GPU:
    EVGA RTX 3080
    690 is the worst nvidia card? what?

    Did that ever actually work?
     

  16. Ragingun

    Ragingun Master Guru

    Messages:
    982
    Likes Received:
    0
    GPU:
    295x2
    My question is do they plan to make this work "backwards compatible" with current DX11 cards? I didn't think DX11 cards could take advantage of any of the DX12 features no different than any other upgraded version of DX.
     
  17. ---TK---

    ---TK--- Ancient Guru

    Messages:
    22,110
    Likes Received:
    2
    GPU:
    2x 980Ti Gaming 1430/7296
    Thats almost 100 mhz higher than my nice clocking 680 sli setup. That is hardly a bad overclock.
     
  18. Agent-A01

    Agent-A01 Ancient Guru

    Messages:
    11,462
    Likes Received:
    963
    GPU:
    3080Ti Strix H20
    He must be new to the tech world.. I remember it being a FX card..
     
  19. thatguy91

    thatguy91 Ancient Guru

    Messages:
    6,643
    Likes Received:
    99
    GPU:
    XFX RX 480 RS 4 GB
    Kind of, if you were lucky and also running the right games :). That was essentially a hack method for DirectX, this method is build into the API itself so it should work a lot better. The only questionable thing is whether it can work in mixed mode, or whether you actually have to have a proper DirectX 12 capable Intel on-die GPU for it to work. If it is the latter, than many of use would out of luck! It would be a bit of a win for AMD APU's though, since I believe the current APU's will be DirectX compatible.

    Intel aren't the best at supporting old hardware, like Ivy-Bridge etc. Going by the past, first gen Haswell will be out of support cycle shortly.
     
  20. fantaskarsef

    fantaskarsef Ancient Guru

    Messages:
    12,523
    Likes Received:
    4,870
    GPU:
    2080Ti @h2o
    And that where it fails in the first place. Because devs have to adapt dx12 first (games running on 11 and 12 I guess), then program sli / cfx support, and then optimizing for a mixture of both... I don't see it happen in our current world of badly / not optimized games and console ports. Way to much effort for way to little gain for the companies.


    That too.


    +1


    With the cards, maybe. This is done software side, so I could probably imagine it to work with older cards, especially those already said to support some dx12 / 11.3 features. But I won't ever see us putting in a 4850 toxic, a gtx 580, and sli 980 for instance ;)
     

Share This Page