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Shockwave: Xbox360 Superior - Playstation 3 Inferior. Xbox360 will outperform PS3

Discussion in 'ATI' started by Guest, May 21, 2005.

  1. Guest

    Guest Guest


    Xbox 360 vs. PS3
    Posted: May 20, 2005 @ 10:37 am (8 hours, 5 minutes ago) By: Major Nelson
    One of the great things about working at Xbox is that we have some of the
    smartest people in the world working on the Xbox 360. When Sony came
    announced the PS3, along with the product specs some of our team started
    looking at some of the numbers to see what they mean. Floating Point,
    shaders, bandwidth..what does it all mean. Clearly there are some numbers
    and stats that mean more to gaming then others, so the team cranked out some
    facts for everyone to absorb. Our world class technology team looked at the
    numbers and claims and decided to do what everyone else does: compare them
    to the PS3. The difference it that these guys are uniquely qualified to do
    so, and can cut through the smoke and mirrors to see what the real deal is.
    To that end, I present this summary, which I have broken up into four parts
    to make it more RSS Reader friendly.

    Warning: Some of this stuff may make your head hurt, but these are the facts
    as they stand right now. Enjoy the read:


    Now that the Xbox 360 and PlayStation 3 specifications have been announced,
    it is possible to do a real world performance comparison of the two systems.

    There are three critical performance aspects of a console:
    .. Central Processing Unit (CPU) performance.
    o The Xbox 360 CPU architecture has three times the general purpose
    processing power of the Cell.
    .. Graphics Processing Unit (GPU) performance
    o The Xbox 360 GPU design is more flexible and it has more processing power
    than the PS3 GPU.
    .. Memory System Bandwidth
    o The memory system bandwidth in Xbox 360 exceeds the PS3's by five times.


    The Xbox 360's CPU has more general purpose processing power because it has
    three general purpose cores, and Cell has just one.


    Cell's claimed advantage is on streaming floating point work which is done
    on its seven DSP processors.


    The Xbox 360 GPU has more processing power than the PS3's. In addition, its
    innovated features contribute to overall rendering performance.


    Xbox 360 has 278.4 GB/s of memory system bandwidth. The PS3 has less than
    one-fifth of Xbox 360's (48 GB/s) of total memory system bandwidth.

    When you break down the numbers, Xbox 360 has provably more performance than
    PS3. Keep in mind that Sony has a track record of over promising and under
    delivering on technical performance. The truth is that both systems pack a
    lot of power for high definition games and entertainment.

    However, hardware performance, while important, is only a third of the
    puzzle. Xbox 360 is a fusion of hardware, software and services. Without the
    software and services to power it, even the most powerful hardware becomes
    inconsequential. Xbox 360 games-by leveraging cutting-edge hardware,
    software, and services-will outperform the PlayStation 3.


    The Xbox 360 processor was designed to give game developers the power that
    they actually need, in an easy to use form. The Cell processor has
    impressive streaming floating-point power that is of limited use for games.

    The majority of game code is a mixture of integer, floating-point, and
    vector math, with lots of branches and random memory accesses. This code is
    best handled by a general purpose CPU with a cache, branch predictor, and
    vector unit.

    The Cell's seven DSPs (what Sony calls SPEs) have no cache, no direct access
    to memory, no branch predictor, and a different instruction set from the PS3's
    main CPU. They are not designed for or efficient at general purpose
    computing. DSPs are not appropriate for game programming.

    Xbox 360 has three general purpose CPU cores. The Cell processor has only

    Xbox 360's CPUs has vector processing power on each CPU core. Each Xbox 360
    core has 128 vector registers per hardware thread, with a dot product
    instruction, and a shared 1-MB L2 cache. The Cell processor's vector
    processing power is mostly on the seven DSPs.

    Dot products are critical to games because they are used in 3D math to
    calculate vector lengths, projections, transformations, and more. The Xbox
    360 CPU has a dot product instruction, where other CPUs such as Cell must
    emulate dot product using multiple instructions.

    Cell's streaming floating-point work is done on its seven DSP processors.
    Since geometry processing is moved to the GPU, the need for streaming
    floating-point work and other DSP style programming in games has dropped

    Just like with the PS2's Emotion Engine, with its missing L2 cache, the Cell
    is designed for a type of game programming that accounts for a minor
    percentage of processing time.

    Sony's CPU is ideal for an environment where 12.5% of the work is
    general-purpose computing and 87.5% of the work is DSP calculations. That
    sort of mix makes sense for video playback or networked waveform analysis,
    but not for games. In fact, when analyzing real games one finds almost the
    opposite distribution of general purpose computing and DSP calculation
    requirements. A relatively small percentage of instructions are actually
    floating point. Of those instructions which are floating-point, very few
    involve processing continuous streams of numbers. Instead they are used in
    tasks like AI and path-finding, which require random access to memory and
    frequent branches, which the DSPs are ill-suited to.

    Based on measurements of running next generation games, only ~10-30% of the
    instructions executed are floating point. The remainders of the instructions
    are load, store, integer, branch, etc. Even fewer of the instructions
    executed are streaming floating point-probably ~5-10%. Cell is optimized for
    streaming floating-point, with 87.5% of its cores good for streaming
    floating-point and nothing else.



    Even ignoring the bandwidth limitations the PS3's GPU is not as powerful as
    the Xbox 360's GPU.

    Below are the specs from Sony's press release regarding the PS3's GPU.

    .. 550 MHz
    .. Independent vertex/pixel shaders
    .. 51 billion dot products per second (total system performance)
    .. 300M transistors
    .. 136 "shader operations" per clock

    The interesting ALU performance numbers are 51 billion dot products per
    second (total system performance), 300M transistors, and more than twice as
    powerful as the 6800 Ultra.

    The 51 billions dot products per cycle were listed on a summary slide of
    total graphics system performance and are assumed to include the Cell
    processor. Sony's calculations seem to assume that the Cell can do a dot
    product per cycle per DSP, despite not having a dot product instruction.

    However, using Sony's claim, 7 dot products per cycle * 3.2 GHz = 22.4
    billion dot products per second for the CPU. That leaves 51 - 22.4 = 28.6
    billion dot products per second that are left over for the GPU. That leaves
    28.6 billion dot products per second / 550 MHz = 52 GPU ALU ops per clock.

    It is important to note that if the RSX ALUs are similar to the GeForce 6800
    ALUs then they work on vector4s, while the Xbox 360 GPU ALUs work on
    vector5s. The total programmable GPU floating point performance for the PS3
    would be 52 ALU ops * 4 floats per op *2 (madd) * 550 MHz = 228.8 GFLOPS
    which is less than the Xbox 360's 48 ALU ops * 5 floats per op * 2 (madd) *
    500 MHz= 240 GFLOPS.

    With the number of transistors being slightly larger on the Xbox 360 GPU
    (330M) it's not surprising that the total programmable GFLOPs number is very


    The PS3 does have the additional 7 DSPs on the Cell to add more floating
    point ops for graphics rendering, but the Xbox 360's three general purpose
    cores with custom D3D and dot product instructions are more customized for
    true graphics related calculations.

    The 6800 Ultra has 16 pixel pipes, 6 vertex pipes, and runs at 400 MHz.
    Given the RSX's 2x better than a 6800 Ultra number and the higher frequency
    of the RSX, one can roughly estimate that it will have 24 pixel shading
    pipes and 4 vertex shading pipes (fewer vertex shading pipes since the Cell
    DSPs will do some vertex shading). If the PS3 GPU keeps the 6800 pixel
    shader pipe co-issue architecture which is hinted at in Sony's press
    release, this again gives it 24 pixel pipes* 2 issued per pipe + 4 vertex
    pipes = 52 dot products per clock in the GPU.

    If the RSX follows the 6800 Ultra route, it will have 24 texture samplers,
    but when in use they take up an ALU slot, making the PS3 GPU in practice
    even less impressive. Even if it does manage to decouple texture fetching
    from ALU co-issue, it won't have enough bandwidth to fetch the textures

    For shader operations per clock, Sony is most likely counting each pixel
    pipe as four ALU operations (co-issued vector+scalar) and a texture
    operation per pixel pipe and 4 scalar operations for each vector pipe, for a
    total of 24 * (4 + 1) + (4*4) = 136 operations per cycle or 136 * 550 = 74.8
    GOps per second.


    Given the Xbox 360 GPU's multithreading and balanced design, you really can't
    compare the two systems in terms of shading operations per clock. However,
    the Xbox 360's GPU can do 48 ALU operations (each can do a vector4 and
    scalar op per clock), 16 texture fetches, 32 control flow operations, and 16
    programmable vertex fetch operations with tessellation per clock for a total
    of 48*2 + 16 + 32 + 16 = 160 operations per cycle or 160 * 500 = 80 GOps per

    Overall, the automatic shader load balancing, memory export features,
    programmable vertex fetching, programmable triangle tesselator, full rate
    texture fetching in the vertex shader, and other "well beyond shader model
    3.0" features of the Xbox 360 GPU should also contribute to overall
    rendering performance.

    The PS3 has 22.4 GB/s of GDDR3 bandwidth and 25.6 GB/s of RDRAM bandwidth
    for a total system bandwidth of 48 GB/s.

    The Xbox 360 has 22.4 GB/s of GDDR3 bandwidth and a 256 GB/s of EDRAM
    bandwidth for a total of 278.4 GB/s total system bandwidth.


    Why does the Xbox 360 have such an extreme amount of bandwidth? Even the
    simplest calculations show that a large amount of bandwidth is consumed by
    the frame buffer. For example, with simple color rendering and Z testing at
    550 MHz the frame buffer alone requires 52.8 GB/s at 8 pixels per clock. The
    PS3's memory bandwidth is insufficient to maintain its GPU's peak rendering
    speed, even without texture and vertex fetches.

    The PS3 uses Z and color compression to try to compensate for the lack of
    memory bandwidth. The problem with Z and color compression is that the
    compression breaks down quickly when rendering complex next-generation 3D

    HDR, alpha-blending, and anti-aliasing require even more memory bandwidth.
    This is why Xbox 360 has 256 GB/s bandwidth reserved just for the frame
    buffer. This allows the Xbox 360 GPU to do Z testing, HDR, and alpha blended
    color rendering with 4X MSAA at full rate and still have the entire main bus
    bandwidth of 22.4 GB/s left over for textures and vertices.

    When you break down the numbers, Xbox 360 has provably more performance than
    PS3. Keep in mind that Sony has a track record of over promising and under
    delivering on technical performance. The truth is that both systems pack a
    lot of power for high definition games and entertainment.

    However, hardware performance, while important, is only a third of the
    puzzle. Xbox 360 is a fusion of hardware, software and services. Without the
    software and services to power it, even the most powerful hardware becomes
    inconsequential. Xbox 360 games-by leveraging cutting-edge hardware,
    software, and services-will outperform the PlayStation 3.
    Guest, May 21, 2005
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  2. Guest

    Paul Heslop Guest

    GET A LIFE!!!
    Paul Heslop, May 21, 2005
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  3. Guest

    Jacob Guest

    According to Japanese news reports, there are rumors that the PS3 will be
    priced at 50,000 yen, or nearly $500 US dollars.
    Jacob, May 22, 2005
  4. Guest

    Boody Bandit Guest

    I'm kewl with that.
    Boody Bandit, May 22, 2005
  5. Guest

    Mattinglyfan Guest

    $460 USD in Japan. Which is cool because they always pay more. It will
    probably be $399 which I can handle.
    Mattinglyfan, May 22, 2005
  6. Guest

    _Carpmaster_ Guest

    Right it will be around $399. Oh yeah, gas prices will also drop to $1.10 a
    gallon. ;)
    _Carpmaster_, May 23, 2005
  7. Guest

    chrisv Guest



    Cross-posting a$$hole.
    chrisv, May 23, 2005
  8. Guest

    Mattinglyfan Guest

    If it is $460 in Japan, why couldn't it be right around $400 in the US?
    Mattinglyfan, May 24, 2005
  9. Guest

    Fisher Guest

    That sounds about right considering we leading edge PC gamers pay that
    much just for a video card. Console gamers have been getting treated
    like the pablum babies that they are for too long. Every Xbox sold
    cost $150.00 to Microsoft. I know they charge a bit more for their
    games but it's still not very good business to sell your hardware at a
    loss. I expect $500.00 may still be at a loss.
    Fisher, May 24, 2005
  10. Guest

    JBDragon Guest

    That's how the Console business model has been all alone. It's not going
    to change anytime soon. There have been deals to get FREE PC's when you
    paid for a year of AOL for example. How do think the Cell Phone industry
    works? Free Phone's or Lower price phones with 1 or 2 year contracts.
    It's the SAME THING. You take a loss on the product and make it up and
    more on the back end.
    JBDragon, May 24, 2005
  11. Guest

    Fisher Guest

    Well, dammit, I want the Nvidia 6800 Ultra for $100.00 then and they
    can sell me a years subscription to some crappy online game instead.
    Fisher, May 24, 2005
  12. Guest

    Dragoncarer Guest

    Don't forget that the PS3 will also have Blu-ray. Blu-ray is gonna be kinda
    expensive for the next six-twelve months at least IMHO. A cheap, viable
    Blu-ray ROM is a far way away.

    If PS3 is released early 2006....I shudder to think of the price. But
    USD500-600 seems probably right.

    I imagine the Xbox will be quite cheaper.

    But then...M$
    Dragoncarer, May 24, 2005
  13. You're an idiot.
    Robert P Holley, May 24, 2005
  14. Guest

    Fisher Guest

    And you're a fucking asshole. What's the prob?
    Fisher, May 24, 2005
  15. Guest

    Boody Bandit Guest

    No Prob.
    He just thinks you're a *fucking* idiot.
    Boody Bandit, May 24, 2005
  16. Guest

    Fisher Guest

    Yea, well, I don't give a *fucking* rat's arse what some tosser on
    usenet thinks. Obviously he didn't like my "pablum babies" comment
    because he is a console pablum fed weenie dickcheese. *fart*
    Fisher, May 25, 2005
  17. Guest

    Mattinglyfan Guest

    You haven't done very much to dispel that "idiot" comment.
    Mattinglyfan, May 25, 2005
  18. Guest

    Fisher Guest

    Maybe because I haven't tried? Der! Briaaaan! My bwain hurts.
    Fisher, May 25, 2005
  19. Of course not, that's why you just replied three times in the same
    thread. I'm sure if you had cared you might have replied twenty times,
    You're an idiot and an embarrassment to PC gamers everywhere.
    Robert P Holley, May 25, 2005
  20. Guest

    Fisher Guest

    I replied not because I care what you think but because I love winding
    you tosspots up.

    I'll go to my grave in shame. :-/
    Fisher, May 26, 2005
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