When AMD launched its Kabini and Temash APUs last year it delivered a compelling cost/performance story, but its power story wasn’t all that impressive. Despite being built out of relatively low power components, nearly all of AMD’s entry level APUs carried 15W TDPs, with a couple weighing in at 8 - 9W and only a single 1GHz dual-core part dropping down to 3.9W. By comparison, Intel was shipping full blown Haswell Ultrabook parts at 15W - offering substantially better CPU performance, in a similar thermal envelope (although at a higher cost). The real disruption for AMD was Intel’s Bay Trail, which showed up with a similar looking micro architecture running at substantially higher clock speeds and TDPs below 8W.

AMD seemed to have all of the right pieces to build a power efficient mobile SoC, but for some reason we weren’t seeing it. Today that begins to change with the the successors to Kabini and Temash.

Codenamed Beema and Mullins, these are the 2014 updates to Kabini and Temash (respectively). Beema is aimed at entry level notebooks, while Mullins targets tablets. For now, both are designed for Windows machines. Although I suspect we’ll eventually see AMD address the native Android market head on, for now AMD is relying on running Android on top of Windows for those who really want it. No word on if/when we’ll get a socketed Beema for entry level desktops.

Like their predecessors, Beema and Mullins combine four low power AMD x86 cores (Puma+ this time, instead of Jaguar) with 128 GCN based Radeon GPU cores. AMD will continue to offer a couple of dual-core SKUs, but they are harvested from a quad-core die. AMD remains unwilling to release official die area figures, but there is a slight increase in transistor count:

AMD/Intel Transistor Count & Die Area Comparison
SoC Process Node Transistor Count Die Area
AMD Zacate TSMC 40nm 450M+ 75mm2
AMD Kabini/Temash TSMC 28nm 914M ~107mm2 (est)
AMD Beema/Mullins GF 28nm 930M ~107mm2 (est)
AMD Llano GF 32nm SOI 1.18B 228mm2
AMD Trinity/Richland GF 32nm SOI 1.30B 246mm2
AMD Kaveri GF 28nm SHP 2.41B 245mm2
Intel Haswell (4C/GT2) Intel 22nm 1.40B 177mm2

I’d expect a similar die size to Kabini/Temash. It’s interesting to note that these SoCs have a transistor count somewhere south of Apple’s A7.

Puma+ is based on the same micro architecture as Jaguar. We’re still looking at a 2-wide OoO design with the same number of execution units and data structures inside the chip. The memory interface remains unchanged as well at 64-bits wide. These new SoCs are still built on the same 28nm process as their predecessor. The process however has seen some improvements. Not only are both the CPU and GPU designs slightly better optimized for lower power operation, but both benefit from improvements to the manufacturing process resulting in substantial decreases in leakage current.

AMD claims a 19% reduction in core leakage/static current for Puma+ compared to Jaguar at 1.2V, and a 38% reduction for the GPU. The drop in leakage directly contributes to a substantially lower power profile for Beema and Mullins.

AMD also went in and tweaked the SoC’s memory interface. Kabini/Temash had a standard PC-like DDR3 memory interface. All of the complexity required for broad memory module compatibility and variations in trace routing was handed by the controller itself. This not only added complexity to the DDR3 interface but power as well. With Beema and Mullins, AMD took a page from the smartphone SoC design guide and traded flexibility for power. These platforms now ship with more strict guidelines as to what sort of memory can be used on board and how traces must be routed. The result is a memory interface that shaves off more than 500mW when in this more strict, low power mode. OEMs looking to ship a design with socketed DRAM can still run the memory interface in a higher power mode to ensure memory compatibility.

These SoCs won’t be available in a PoP configuration unfortunately - OEMs will have to rely on discrete DRAM packages rather than a fully integrated solution. Beema/Mullins also show up to a 200mW reduction in power consumed by the display interface compared to Kabini/Temash.

The combination of all of this is 20% lower idle power compared to the previous generation of AMD entry level and low power APUs. AMD put together a nice graph illustrating its progress over the years:

Beema and Mullins are definitely in a good place, however they still do consume more power at idle than the smartphone SoCs we typically find in iOS and Android tablets. AMD isolated APU power for the graph above and is using an “eReader” workload (aka display on but not animating, system otherwise idle). It just so happens I gathered similar data for our 2013 Nexus 7 review. The workloads and measurements are different (AMD isolates APU power, I’m looking at total platform power minus display) but it’s enough to put things in perspective:

SoC Idle Power Comparison

AMD has dropped power consumption considerably over the years, but it’s still not as power efficient as high end mobile silicon.

AMD sees no value in supporting Microsoft's Connected Standby standard at this point, which makes sense given the limited success of Windows 8 tablets. Once again this seems to point to AMD eventually adopting Android for its tablet aspirations.

Looking forward, AMD has more tricks up its sleeve to continue to drive power down. Most interesting on the list? We’ll see an integrated voltage regulator (ala Haswell’s FIVR) from AMD in 2015.

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  • vlad42 - Tuesday, April 29, 2014 - link

    Hey Anand,
    Do you know if connected standby was enabled on the Mullins tablet you tested? I’ve heard that AMD has not yet developed the connected standby drivers yet. If this is the case, then shouldn’t that be noted in the power consumption test? Given the improvements Intel sees when connected standby is enabled, it definitely looks like the Mullins tablet was not using connected standby.
  • Anand Lal Shimpi - Tuesday, April 29, 2014 - link

    No CS, although I believe Mullins could theoretically support it. For this particular test there should be no advantage to having CS, we're just looking at short/active idle power usage.
  • Anand Lal Shimpi - Tuesday, April 29, 2014 - link

    Correction - there are no plans to support CS, AMD doesn't see value in it.
  • tomsworkshop - Tuesday, April 29, 2014 - link

    this low power but high performance tiny little chip can be fit on something like the raspberry pi, we can build a really small micro pc with such hardware.
  • mfoley93 - Wednesday, April 30, 2014 - link

    They aren't low power enough yet, so in the mean time, I suspect nVIDIA's Jetson board based off the Tegra K1 might fit the spot you are thinking of. The board is significantly larger, but its powerful enought to justify that. It's also more in the Beagleboard/Pandaboard segment, being aimed at embedded development and not education.

  • tomsworkshop - Thursday, May 1, 2014 - link

    The Tegra K1 rated at 5W TDP, the Mullins rated at 3.95W - 4.5W TDP, i think they should be low power enough for a single board computer, i saw the price for the Jetson TK1, it was 3 times higher than the Raspberry Pi, hope that AMD will come out something at the middle of the Raspberry Pi and Jetson TK1, with the price lower than the Jetson TK1, and the performance better than the Raspberry Pi.
  • nemi2 - Tuesday, April 29, 2014 - link

    It's good to see AMD catching up but the power consumption may still be a deciding factor when choosing between this and Baytrail - I look forward to a full review of release hardware. The other area of concern is that the Baytrail successor Airmont (with shrink to 14nm and ~30% power savings) will also be out in 2014 so AMD may only have 0-3 months at parity/competitiveness with intel.
  • H2323 - Tuesday, April 29, 2014 - link

    Yes these are shorty terms wins, but 14nm airmont is late and will miss back to school and be just in time for christmas, AMD will net some revenue on this and still retain GPU lead with baytrail
  • R3MF - Tuesday, April 29, 2014 - link

    a four-core mullins in an 8" tablet chassis with 4GB of memory and bios support for a 64bit ubuntu would be an awesome thing.
  • MrSpadge - Tuesday, April 29, 2014 - link

    I'd rather have a Thinkpad 10 + Win 8.1 with this, at least as an option instead of Bay Trail. If the actual product is as impressive as the preview.

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