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why is the 2900xt slower than the 8800gtx

Discussion in 'Graphics Cards' started by Darkmind, Sep 25, 2007.

  1. Darkmind New Member

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    Spec wise it kicks ass except the amount of ROPs. Is it the amount of ROP's that made it so it wouldn't take the performance crown? 16 vs 24. But it has 320 shader processors (clocked at 742mhz), while the 8800gtx is 128 shader processors at 1.35ghz.

    I guess I must've answered my own question? Hmm
  2. v-zero Guest

    It's not the ROPs, it's the design. Those "320 shaders" are deceptive - most are not fully developed shaders, and so do not have anywhere near the potency of each shader in the G80 based cards. As such, the technically superior G80 will always win.
  3. R-T-B

    R-T-B

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    I always thought it wasn't so much that the shader were less developed as it was that ATI went with a less efficient super-scalar architechture that their dispatcher isn't so efficient at handling. That and the slower clock speeds of the shaders does put them at a disadvantage.

    If you want to go by paper, technically the ATI piece of hardware is "technically superior" in that it has more transistors and thus more features (tesselator and all that). But those features aren't part of the DX10 spec, and as such probably won't be used in many games. Also, this superiority in features does nothing when it comes to FPS, where NVIDIA consistently wins for the reasons I listed above.

    Maybe I misread a few things though, that's just how I understood it from the article at anandtech.
  4. Matsu New Member

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    If you are talking about AA performance then the R600 isn't supposed to be good at Multi sampling AA ( I think that is what its called). It is supposed to be good at Shader AA revolve. I think it works by using the shaders to do the AA instead.
  5. KennyT772

    KennyT772 New Member

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    The 2900 is slower one because of the superscalar design - parallelism is key. If the 2900 had half the shaders but running twice as fast you would see performance increase by 20%.

    Also the 2900 is a brand new card compared to the 8800. Ati has simply not had the same amount of time to optimize and improve the drivers as nVidia has. I'm not just talking about making the game run as fast as possible, but also various quality settings, various system configurations, etc.
  6. R-T-B

    R-T-B

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    Ah, I forgot about the shaders. Honestly I don't use AA at anything over 1600x1200 because I don't notice it so that doesn't effect me. But yeah, it doesn't have any MSAA hardware, it just uses shaders, so it'll perform far better in none AA benchmarks.
  7. niko084

    niko084

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    Also remember it depends on what the game itself was tweaked for...

    The 8800 has been out long enough for quite a few new games to be built to perform well on it, while the 2900 was not in existence. Thats another piece that helps..
  8. largon New Member

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    Basically the shaders on R600 can't calculate as complex functions as those on G80 and on top of that they do less work per clock.
  9. v-zero Guest

    A said earlier, most of the shaders in the R600 design are very limited, with a few powerful shaders (more similar to the 8800's) carrying much of the load. Also, the lack of proper AA support causes massive problems.
  10. Matsu New Member

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    Games that actually use shaders to do AA the ATI cards won't look as bad.
  11. Grings

    Grings New Member

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    In hardocp's call of juarez test the 2900 took less of a hit with aa on than a gts, so it cant be all bad
    [​IMG]
  12. kwchang007

    kwchang007 New Member

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    @grings...it has a larger bus size. Shouldn't it be better at AA?

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