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

Quote:McMulle then explained DX12’s Multiadapter functionalities. DX12 will support Linked GPUs and Unlinked GPUs. Linked GPUs is similar to what we have today with SLI and Crossfire. However, via Unlinked GPUs, PC gamers will be able to use GPUs from different vendors like AMD and Intel.

(05-06-2015, 08:44 PM)ocre Wrote: are you sure that is the right link rollo?

Quote:DirectX 12 offers no hand-holding here, if the developer doesn't come up with an ingenious way to optimize mixed-GPU performance, then there won't be any scaling at all. This makes me wonder - what incentive is there for developers or GPU vendors to properly implement it? I have serious doubts that any GPU vendor would allocate resources to help developers with GPU scaling that would let people buy competing products to boost performance. I also don't think developers, who develop for consoles first these days, feel like spending a lot of their own time (= money) on such a feature. Recent releases have shown that many games barely make it through the console porting process, with the console user interface still in place and tons of bugs and performance issues. Let's hope that I am wrong and upcoming DirectX 12 titles finally free us from the GPU vendor lock in.

Quote:The idea of having a GTX 980 and a R9 390X seems amazing, as you can take full advantage of any and all games. If a game favors Nvidia use the 980 as the primary card or vice-versa. In the case of Ashes of the Singularity the game so heavily favors AMD that having a GeForce graphics card working for you is almost a disadvantage.

Yes, the 390X/980 combo was 48% faster than a single 390X, but two 390Xs were 68% faster. Still, the ability to mix and match graphics cards opens up a world of possibility.

Realizing we've only tested a small number of the possible GPU combinations and the games that will follow in the coming year, there's more to be seen but for now Ashes has given us a nice peak of what's to come. You can expect more weird and wonderful GPU combinations when this and other DX12 games roll out in 2016.

Quote:For those of you that wonder, the left side colors flashing are FCAT color tags, each rendered frame gets one color assigned in a strict sequence. Obviously you can see screen-tearing with VSYNC off in this video, hence it looks worse then it is with VSYNC/FreeSync/Gsync enabled.

That's it for this article, I decided to cut off the game test until the SYNC issue is solved on AMDs side. The good news is this. Last week I presented this behaviour to AMD. AMD has successfully identified the issue. Radeon Software 16.1 / 16.2 does not the DX12 DirectFlip feature, which is mandatory and the solve to the specific VSYNC situation we ran in to. For Nvidia it seems that ASYNC compute shaders are not working and we have to winder as to why anno February 2016 still is the case ?

AMD intends to resolve this issue in a future driver update, after which we'll update this article. The same goes for Nvidia with ASYNC compute support, or better yet the lack of it.

(03-15-2016, 01:12 AM)SteelCrysis Wrote: Stardock is working on their own version of AMD + Nvidia multi-GPU enabling: http://www.neowin.net/news/stardock-developing-software-to-enable-mixed-multi-gpu-setups