AMD: Pirate Islands (R* 3** series) Speculation/Rumor Thread

Discussion in 'Architecture and Products' started by iMacmatician, Apr 10, 2014.

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  1. ToTTenTranz

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    Tonga has 700M more transistors than Tahiti. That's roughly the equivalent of a full G92 GPU.
    I'd have a hard time believing that color compression + Audio DSPs + 2 extra tesselation engines + 6 ACEs + other optimizations would take 700M transistors. Even more considering how the Crossbar was apparently taken away.
     
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  2. AlBran

    AlBran Ferro-Fibrous
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    hm... zoom and enhance XD
    http://i.imgur.com/Q5MVBsz.jpg
     
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  3. Esrever

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    Most likely there are just a lot of different power control circuitry that may or may not be enabled. The move from Kaveri to Carrizo had a huge increase in transistor count too without increasing the core configuration significantly.
     
  4. ToTTenTranz

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    Yet I failed to mention that from Tahiti to Tonga the DP output went from 4:1 to 16:1. Tonga has 1/4th the DP output of Tahiti.

    Plus, Carrizo brought an embedded Southbridge, new CPU cores with 15% higher IPC, AVFS, a secure Processor with an ARM core + cache + ROM inside and there's a chance the chip needs hardware to comply with both DDR3 and DDR4 memory (the same chip will probably be used for Bristol Ridge).
    I don't really think the Kaveri -> Carrizo transition is comparable.
     
  5. Esrever

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    The CPU cores are smaller than before. The memory controller isn't larger. The ARM core is insignificant. A billion more transistors just for memory bus and southbridge?
     
  6. 3dilettante

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    The most recent version of GCN did up some of the complexity of the scalar unit's pipeline since it supports scalar writes, and various updates that could offset the reduction in DP throughput at the CU level, which may apply to the Tahiti/Tonga and Kaveri/Carrizo comparison.
    Carrizo's L2 caches are lower in capacity, but the x86 cores themselves should be relatively larger due to increases in L1 capacity and general tweaks to the pipeline.

    One possible change is the introduction of HDL to the APU side, which I am not clear if a similar change in implementation has occurred on the discrete side--although it's been long enough that there should have been at least iterative changes in the implementation of the designs.
    That might lead to a change in terms of how units are implemented with more dense layout.

    Another maybe that can compound the HDL/implementation evolution factors is a question of counting methodology:
    http://www.anandtech.com/show/7003/the-haswell-review-intel-core-i74770k-i54560k-tested/5
    This is a decent amount of error margin on top of design changes and new integrated hardware. It has not been clear all the time which count was being used, and HDL might increase the number of process transistors needed for a given schematic count.

    On top of that, let's note that AMD has a history of widening the error bars further:
    http://techreport.com/news/22100/amd-corrects-muffed-bulldozer-transistor-count
     
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  7. no-X

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    That's true. As for delta color compression AMD states "5-7% improvement on games for modest silicon area (0.2%)" for Carrizo.
     
  8. Jawed

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    GPUs are fully synthesised. Is that description of schematic/layout at all relevant to a synthesised implementation?
     
  9. 3dilettante

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    For some of the Nvidia GPU releases, it was intimated that this was not wholly the case. Perhaps it is for AMD GPUs.
     
  10. ToTTenTranz

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    The CPU cores and the memory controller are smaller because they're denser, not because they have less transistors. We were discussing transistor count. Carrizo's area is actually very similar to Kaveri's. A Cortex A5 + cache + ROM + glue logic isn't that much insignificant. The difference between Carrizo and Kaveri isn't 1 billion transistors, it's less than 700 million.
     
  11. ToTTenTranz

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  12. ToTTenTranz

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    In what should be another indicator that Tonga will have its lifetime extended into 2016 and beyond, AMD just launched their GPU virtualization FirePro cards and they both use that chip.
    One of the cards uses a dual-Tonga configuration. This probably won't come to the home market, but a ~$350 dual-Tonga card would certainly be a cheap and compact solution for VR.
     
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  13. Esrever

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    Anyone knows what AMD is doing with the fully enabled chips for the 360 and 370 since they still don't have a 360x or 370x and both of the former cards are salvaged parts. Although the price segments for that market is very crowed, I would think AMD would rather not only sell cut down chips if they have full working chips.
     
  14. AlBran

    AlBran Ferro-Fibrous
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    Saving them for the 4xx refresh?
     
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  15. kalelovil

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    A R9 370X desktop card does exist, but it is only being sold in China and Korea.
    Although it is difficult to find anything other than the iMac using one, there are a few current mobile cards using a fully enabled Bonaire chip: R9 M380, R9 M385, R9 M385X, Firepro M6100.
     
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