The Platform

From a design perspective, Carrizo is the biggest departure to AMD’s APU line since the introduction of Bulldozer cores. While the underlying principle of two INT pipes and a shared FP pipe between dual schedulers is still present, the fundamental design behind the cores, the caches and the libraries have all changed. Part of this was covered at ISSCC, which we will also revisit here.

On a high level, Carrizo will be made at the 28nm node using a similar silicon tapered metal stack more akin to a GPU design rather than a CPU design. The new FP4 package will be used, but this will be shared with Carrizo-L, the new but currently unreleased lower-powered ‘Cat’ core based platform that will play in similar markets for lower cost systems. The two FP4 models are designed to be almost plug-and-play, simplifying designs for OEMs. All Carrizo APUs currently have four Excavator cores, more commonly referred to as a dual module design, and as a result the overall design will have 2MB of L2 cache.

Each Carrizo APU will feature AMD’s Graphics Core Next 1.2 architecture, listed above as 3rd Gen GCN, with up to 512 streaming processors in the top end design. Memory will still be dual channel, but at DDR3-2133. As noted in the previous slides where AMD tested on DDR3-1600, probing the memory power draw and seeing what OEMs decide to use an important aspect we wish to test. In terms of compute, AMD states that Carrizo is designed to meet the full HSA 1.0 specification as was released earlier this year. Barring any significant deviations in the specification, AMD expects Carrizo to be certified when the final version is ratified.

Carrizo integrates the southbridge/IO hub into the silicon design of the die itself, rather than a separate on package design. This brings the southbridge down from 40nm+ to 28nm, saving power and reducing long distance wires between the processor and the IO hub. This also allows the CPU to control the voltage and frequency of the southbridge more than before, offering further potential power saving improvements.  Carrizo will also support three displays, allowing for potentially interesting combinations when it comes to more office oriented products and docks. TrueAudio is also present, although the number of titles that support it is few and the quality of both audio codecs and laptop speakers leaves a lot to be desired. Hopefully we will see the TrueAudio DSP opened up in an SDK at some point, allowing more than just specific developers to work with it.

External graphics is supported by a PCIe 3.0 x8 interface, and the system relies on three main rails for voltage across the SoC which allows for separate voltage binning of each of the parts. AMD’s Secure Processor, with cryptography acceleration, secure boot and BitLocker support are all in the mix.

AMD Launches Carrizo: The Laptop Leap of Efficiency Efficiency and Die Area Savings
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  • FlushedBubblyJock - Tuesday, June 9, 2015 - link

    amazing how a critically correct comment turns into an angry ranting conspiracy from you
  • BillyONeal - Wednesday, June 3, 2015 - link

    This is a preview piece. They don't have empirical data because the hardware isn't in actual devices yet. Look at any of AT's IDF coverage and you'll see basically the exact same thing.
  • Refuge - Wednesday, June 3, 2015 - link

    nothing has been released yet. but it was announced. This is a news site, you think they are just going to ignore AMD's product announcement? That would be considered "Not doing their job"

    They go through the claims, explain them, try to see if they are plausible with what little information they have. I like these articles, it gives me something to digest while I wait for a in depth review, and when I go to read said review I know exactly what information I'm most interested in.
  • KaarlisK - Wednesday, June 3, 2015 - link

    About adaptive clocking.
    Power is not saved by reducing frequency by 5% for 1% of the time.
    Power is saved by reducing the voltage margin (increasing frequency at the same voltage) _all_ the time.
    Also, when the voltage instability occurs, only frequency is reduced. The requested voltage, IMHO, does not change.
  • ingwe - Wednesday, June 3, 2015 - link

    Interesting. That makes more sense for sure.
  • name99 - Monday, June 8, 2015 - link

    It seems like a variant of this should be widely applicable (especially if AMD have patents on exactly what they do). What I have in mind is that when you detect droop rather than dynamically change the frequency (which is hard and requires at least some cycles) you simply freeze the entire chip's clock at the central distribution point --- for one cycle you just hold everything at zero rather than transitioning to one and back. This will give the capacitors time to recover from the droop (and obviously the principle can be extended to freeze the clock for two cycles or even more if that's how long it takes for the capacitors to recover).

    This seems like it should allow you to run pretty damn close to the minimum necessary voltage --- basically all you now need is enough margin to ensure that you don't overdraw within a worst case single-cycle. But you don't need to provision for 3+ worst-case cycles, and you don't need the alternative of fancy check-point and recovery mechanisms.
  • KaarlisK - Wednesday, June 3, 2015 - link

    About that power plane.
    "In yet more effort to suction power out of the system, the GPU will have its own dedicated voltage plane as part of the system, rather than a separate voltage island requiring its own power delivery mechanism as before"
    As I understand it, "before" = same power plane/island as other parts of the SoC.
  • Gadgety - Wednesday, June 3, 2015 - link

    Great read and analysis given the fact that actual units are not available for testing.

    As a consumer looking for use of Carrizo beyond laptops, provided AMD releases it for consumers, it could be a nice living room HTPC/light gaming unit.
  • Laxaa - Wednesday, June 3, 2015 - link

    I would buy a Dell XPS13-esque machine with this(i.e. high quality materials, good design and a high res screen)
  • Will Robinson - Wednesday, June 3, 2015 - link

    According to ShintelDK and Chizow...the above article results are from an Intel chip and AT have been paid to lie and say its Carrizo because their lives would have no meaning if it is a good product from AMD.

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