Report: AMD Carrizo APUs To Get Stacked On-Die Memory

Perhaps it's an unusual source, but Bits 'n Chips from Italy has reported that AMD might be using stacked-DRAM memory in its upcoming Carrizo APUs. In itself, this shouldn't be particularly surprising – AMD is very actively pushing the Heterogeneous System Architecture.

The concept of the Heterogeneous System Architecture is that the CPU and GPU cores all have equal access to the system memory, where they can work together without each core being assigned a specific part of the memory, but where both are able to address any part of the memory at any time. This promises to allow for much higher performance levels, where the GPU can take care of highly parallelized tasks, and the CPU can take care of serial tasks. Such an architecture will really shine when some of the memory is on-die, delivering significantly lower latencies.

The Italian source indicates that having stacked on-die memory will lead to more cost-effective performance compared with on-die L3 cache. This will certainly be due to the more efficient use of the given hardware. The bulk of system memory would still be placed on DDR3, mainly because on-die memory will only add up to somewhere around 128 MB or 256 MB. The report also mentions the ability to stick to DDR3 for the system memory, as opposed to the much more expensive DDR4.

According to the report, the Carrizo APUs will be fabricated on a 28 nm lithographic process, while the stacked-DRAM will be fabricated on a 20 nm process.

Other sources also indicate that some of the Carrizo APUs will have the FCH on-die. We wonder how long it will take before we have all the required parts on-die, essentially creating SoC's (System-on-a-Chip).

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Niels Broekhuijsen

Niels Broekhuijsen is a Contributing Writer for Tom's Hardware US. He reviews cases, water cooling and pc builds.

  • SteelCity1981
    Not surprising Carrizo APUs will stick with DDR3. AMD always waits a year or two for new gen DRAM prices to go down before using it.
  • InvalidError
    Since many of Intel's roadmaps seemed to indicate Intel was planning to make their 128MB Crystalwell L4$/GDR standard across most of their lineup next year, I would have been more surprised if AMD did not announce something similar to avoid falling even further behind.
  • ykki
    Your move, Intel.
  • Menigmand
    They should call it AMD Chorrizo..
  • CaptainTom
    Please god let it be so!
  • PEJUman
    Most CPU benches for intel does not seem to scale with memory bandwidth (at least when compared to AMD APUs). I think AMD processors would benefit a lot more from on package DRAM (ala crystalwell); who knows, maybe this will allow them to finally catch-up to intel again. We really need AMD.

    Intel have a tendency to coast when allowed. It was athlon that drives them into the CORE microarch, and abandon netburst. Now we have the sandy-ivy-haswell coast again...
  • InvalidError
    13724003 said:
    Most CPU benches for intel does not seem to scale with memory bandwidth
    But their IGP does.

    Most desktop applications require a balance between bandwidth, latency and processing power. Once you pass the typical bandwidth and latency requirements for typical workloads for a given architecture, benefits drop off sharply. Intel simply happens to be a few miles ahead of AMD at decoupling their CPUs from memory latency and bandwidth under most circumstances.

    GPUs on the other hand are almost entirely dictated by bandwidth since almost every computational challenge GPUs face can be made easier and faster with more, faster memory to cache results and duplicate frequently accessed items across memory channels to accommodate more concurrent accesses.
  • danwat1234
    AMD needs to make some ~47W TDP mobile APUs, not just up to 35W.
  • hannibal
    Yep... Expensive memory in budget class computer is not smart idea ;-)
  • knowom
    AMD still needs to get it's ducks in a row in terms of power efficiency because it's miles behind Intel in terms of clock for clock basis with the right hardware and know how Intel CPU's simply run at much better voltages for their clock for clock performance output.