Xbox Series X [XBSX] [Release November 10 2020]

Discussion in 'Console Technology' started by Megadrive1988, Dec 13, 2019.

  1. Silent_Buddha

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    Nor surprising. Designing GPUs is as much art as science. It's about finding a balance of components within the limitations of transistor budget and ancillary technologies (like memory speeds).

    No matter what balance is struck, any given GPU will perform better or worse depending on what parts/components of the GPU are stressed in any given game/scenario.

    Because GPUs are a balancing act, scaling one factor up without also scaling up other facets of the GPU is unlikely to see linear scaling (as that factor will become increasingly limited by other factors). And in the rare occasions you do have linear scaling, it won't infinitely scale linearly (eventually the factor you are scaling will become limited by other factors).

    Both the PS5 and XBS systems are engineered with a certain balance of features that each engineering team felt was the best way to spend their transistors combined with the level and cost of ancillary technology to be used. Each are likely targeting different ideas about how game rendering will evolve over the generation. Neither architecture will be perfectly utilized because each individual game developer has different ideas about how they want to render their games or even what their game rendering budget requires.

    In other words, overclocking an existing GPU (to use an easy example) is unlikely to show how effective the increased clocks of the PS5 are. Likewise, examining increased CU counts on PC GPUs is unlikely to show how effective the wider architecture of the XBS-X is. Especially if the comparison is between a fully enabled GPU versus a cut down salvage GPU. And even less informative if the comparison is between different GPUs of the same family. It may or may not give some hints of how the different choices will impact rendering, but it's unlikely to illuminate us on how they actually effect rendering.

    What I find most interesting thus far is how evenly the different architectures perform despite the differences in engineering choices made. Much of that comes down to the fact that the architectures are far more similar than they are different. But a part is also the fact that for multiplatform games (the only ones where direct comparisons are possible) it's in the developers best interest to have the game run well on all platforms it releases on.

    It does make me wonder if we'll see distinctly different approaches to how a scene is rendered in platform exclusive games towards the mid to end of the generation. Basically the exclusives that will start development after the launch of the current generation of consoles.

    Regards,
    SB
     
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  2. invictis

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    And the other factor is that both the XSX and PS5 are using some RDNA 1 and some RDNA 2 parts, wether is the front end, or back end or ROPs.
    So that introduces another variable.

    I think from a typical GPU and CPU point of view, there isn't much between them, and that being shown so far with the actual games.
    What I am interested to see is if other features such as Mesh Shaders, VRS, SFS and ML on the XSX as well as Primitive Shaders on PS5 (don't have much more to add on the PS5 side as Sony just won't talk about their console tech) get adopted by devs and incorporated into engines, and if this may give an advantage over just the raw GPU difference.
    But there's no guarantees that they will be. Devs are generally slow at adopting new features. The slow uptake on DLSS and Ray Tracing for instance.

    From everything you hear, I expect that Turn 10 have incorporated alot of these features into the Forzatech engine, and you would expect idtech 7 to be built around showcasing DX12U features.

    Fun times ahead.
     
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  3. thicc_gaf

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    If the PS5 has more die area dedicated to ROPs then that's because proportionally speaking, it has a smaller APU than Series X but ROP units aren't going to change in size to scale with the CU counts. I mean, they're ROPs, they have their function and a set silicon/transistor budget that's going to stay more or less fixed.

    It would only seem like Series X's are smaller because it has a larger APU its ROPs are contained in (due to higher CU count).

    Performance actually can scale with clock increases; however the real point is that the scaling is not linear and at some point you run into a wall where you're exerting a lot more power for minimum performance gains. On some GPUs, this actually starts to crater performance long-term.

    PS5 still has to adhere to these laws of physics even if it's using supplementary features like Smart Shift to handle distribution of power load between CPU and GPU of the system.
     
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  4. BRiT

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    The ROP implementations changed between RDNA1 and RDNA2. I believe that is what is being referenced there.
     
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  5. ToTTenTranz

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    It's not proportionally larger, it's larger in absolute terms. The PS5 has more absolute die area dedicated to ROPs than the Series X.

    On a "macroscopic" level, it looks like the SeriesX is using a similar arrangement as the Navi 2x chips ("RB+"), which has 2 depth/stencil ROPs per color ROP, whereas the PS5 has 4 depth/stencil ROPs per color ROP which is similar to previous GPUs (I'm tracking that proportion back to at least VLIW4 Cayman).



    This seems like an area saving procedure as we effectively saw the depth/stencil ROPs being halved from Navi 10 to Navi 22 without a substantial loss of performance (though it could change depending on the load).

    Of course, on the PS5 side these are conjectures based on photographs where each pixel corresponds to >1500 transistors, so AFAIK we don't really have any means to be sure.
     
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