The A9X SoC & More To Come

Finally, as everyone is undoubtedly eagerly anticipating our look at the A9X SoC inside the iPad Pro, let’s take a very quick look at what we know about the SoC so far. There’s a bit of a limit to what we can do blindly via just software, but I’m hoping that the eventual A9X die shots will confirm some of our suspicions on A9X’s configuration.

Apple SoC Comparison
  A9X A9 A8X A6X
CPU 2x Twister 2x Twister 3x Typhoon 2x Swift
CPU Clockspeed 2.26GHz 1.85GHz 1.5GHz 1.3GHz
GPU PVR 10 cluster Series7? PVR GT7600 Apple/PVR GXA6850 PVR SGX554 MP4
Memory Bus Width 128-bit 64-bit 128-bit 128-bit
Memory Bandwidth 51.2GB/sec 25.6GB/sec 25.6GB/sec 17.1GB/sec
L2 Cache 3MB 3MB 2MB 1MB
Manufacturing Process Unknown
(TSMC 16nm or Samsung 14nm)
TSMC 16nm &
Samsung 14nm
TSMC 20nm Samsung 32nm

First and foremost, the most unexpected news here is that unlike A8X, A9X is not packing a triple-core CPU. Instead A9X drops back down to just a pair of Twister CPU cores. The twist here is that relative to A8X and A9, Apple has cranked up their CPU clockspeeds. Way, way up. Whereas the iPad Air 2 (A8X) shipped at 1.5GHz and the iPhone 6s (A9) at 1.85GHz, the A9X sees Apple push their clockspeed to 2.26GHz. Not counting the architectural changes, this is 22% higher clocked than the A9 and 51% higher than the A8X.

The fact that Apple dropped back down to 2 CPU cores is unexpected given that we don’t expect Apple to ever go backwards in such a fashion, and while we’ll never know the official reason for everything Apple does, in retrospect I’m starting to think that A8X was an anomaly and Apple didn’t really want a tri-core CPU in the first place. A8X came at a time where Apple was bound by TSMC’s 20nm process and couldn’t drive up their clockspeeds without vastly increasing power consumption, so a third core was a far more power effective option.

WebXPRT 2013 (Chrome/Safari/IE)

Basemark OS II 2.0 - Overall

By comparison, with the FinFET process Apple is using here – and given the lower volume of A9X I don’t have reason to believe it’s dual-sourced, so it’s either TSMC or Samsung – Apple has been free to increase their clockspeeds substantially. At the same time these FinFET processes are still new and yields won’t be great, so there is a strong incentive to keep die sizes down to keep yields up, and adding a third core would only make that harder. If I had to guess, Apple only wanted two cores to begin with – this makes it easier for developers knowing that they only have two cores to work with – and that it’s A8X that is the anomaly.

Otherwise a highly clocked CPU is far more in-line with Apple’s design philosophy as it means that A9X is capable of amazing single-threaded performance – and keep in mind that we’re talking ARM Cortex-A57-like clockspeeds for a CPU that gets much more work done per cycle – so what we see here makes a lot of sense. Plus with iPad Pro in particular Apple has more battery capacity to sustain the power draw of a higher clocked SoC, and more surface area to dissipate that heat, so the usual concerns about power and cooling aren’t quite as pressing. I do wonder if this will impact multitasking performance much, but given what Twister is capable of, I’m not nearly ready to write off a dual-core Twister implementation clocked this high.

Moving on, as is customary for the X-series SoCs from Apple, A9X features what I believe to be a wider 128-bit LPDDR4 memory bus. The memory bandwidth numbers clearly point to a wider bus, and Apple needs the bandwidth to feed a more powerful GPU.

Geekbench 3 Memory Bandwidth Comparison (1 thread)
  Stream Copy Stream Scale Stream Add Stream Triad
Apple A9X 2.26GHz 20.8 GB/s 15.0 GB/s 15.3 GB/s 15.1 GB/s
Apple A8X 1.5GHz 14.2 GB/s 7.44 GB/s 7.54 GB/s 7.49 GB/s
A9X Advantage 46.4% 101% 103% 102%

Which brings us to the last bit of our preview, the GPU. Apple went with a 6 cluster PowerVR Series7 design on A9, and for A9X they have gone with a larger design. Without a die photo it’s basically impossible to determine how many clusters are in use since clockspeed plays such an important role. What we do know is that GPU performance relative to A9 has pretty much doubled, which once again is right in-line with Apple’s usual design goals.

GFXBench 3.0 Manhattan (Offscreen)

Given what Apple has done with clockspeed on Twister, for the moment I am staking my bet on it being a 10 cluster design with a higher GPU clockspeed than A9 giving us the rest of the performance boost. To be clear here this could also be a 12 cluster design at a similar clockspeed or even an 8 cluster design clocked far higher – we’ll need die shots to confirm – but given all of the options it’s a 10 cluster design that is the best balance between die size and clockspeed, and it would also be the biggest curveball Apple could throw. It should also be noted that PowerVR Series7 certainly supports such a configuration since it’s scalable from 2 to 16 clusters, although in Imagination’s official product catalog they don’t have a name for such a configuration. So for the moment I’m simply calling it a 10 cluster Series7.

Anyhow, we’ll be back later with a full review of the iPad Pro, including the pros and cons of Apple’s first large-format, productivity-oriented tablet, and a full breakdown of the A9X SoC. So until then stay tuned.

Taking Notes With iPad Pro
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  • Jukens - Monday, November 23, 2015 - link

    Great read, thanks. Some excellent points.
  • dsumanik - Sunday, December 27, 2015 - link

    Boo hoo akdj! My original post was not intended to bash apple, it was to highlight the significant, and PAID FOR APPLE BIAS Mr. Ho continues to spew forth onto this formerly great online publication. All his apple articles read the same way:

    - positive without fail, zero negatives
    - attractively laid out marketing photos, which he claims aren't manipulated
    - exif info tagged by Lightroom, which means they WERE processed

    If the journalists around here stop posting stupid paid for advertisements disguised as fake reviews, ill gladly stop posting stupid comments calling BS on it.
  • akdj - Tuesday, December 29, 2015 - link

    No need to Boo Hoo me dsu, it's you, the one that should be wasting away - blubbering in your closet. Unreal, complete and utter ignorance
    There's "No pay to advertise for Apple!" Apple doesn't pay journalists, especially smaller, more direct/geek sites like Anandtech, my apologies to the crew I don't mean to demean the value of your site. It's special and has been over the years in a sorta way others aren't.

    So, your dumbass 'reason one' it's not a formerly great site. It continues to be the best

    As for #2 --- I certainly didn't read this 'preview' without fail or zero negatives. He couldn't keep up with mathematic equations and other 'note taking' tasks with the unit, didn't like the grime that formed on the pencil after a while and shading while acceptable isn't an exact science with digital pencils.
    As far as marketing photos, of course they're processed. EVERY photo posted, even in my copy of LR shows manipulation. Of course, shooting with a 18, 20, 24 or whatever megapixel cam allows for extensive cropping. One manipulation you're seeing in the metadata. Size change. It's not like they're applying some sort of brilliant light leak to make it look like its sent from the heavens dude. It's. Gray. Carpet.

    Then I look back on reviews, extensive reviews like the SP4 or the MS Book --- both highly praised, both well received and extremely well 'dressed up' for their photoshoot! :rolleyes:
    Exit tagged by LR means nothing more than a quick crop and easy straightening or lens correction. It wasn't extensively manipulated by LR, How would I know? I own one and my carpet is damn near the same carpet in my studio. I laid it on the floor and shot it with a Canon S95 (older P&S), Canon 5d mkIII & Sony RX v4 (another small but 1" sensor P&S with an extensively brighter lens than the the older S95)
    Every. Image. Looked. Identical!
    This is a tablet man. Take your panties outta the bunch, drop your conspiracy theories or, better yet, find a new site that's not "paid by Cupertino" --- and we'll see ya back in a couple of weeks

    There's a common denominator though -- iPhones and iPads are the highest grossing, largest selling electronic units in history. And each time the former drops, a new record is set. While iPads have dropped a couple million a quarter, they're still quadrupling the competition in three months compared to the other OEMs yearly results!
    The iPad and iPhone are backed by the best app selection, curated App Store and apps that are automatically optimized (nearly, some work in Xcode, though very simple) for each and every display sold by Apple's iOS range. In other words, they're absolutely king of the hill and there's a very good reason. And it's not that there's nearly 100,000,000 dumb people yearly buying one or both products. iPads tend to last a LONG time. My original still works perfectly and maintains 8-10 hours of battery life. My iPad 2, same thing. No problems and relegated to the kids
    I use them for business so I've got more than the normal civilian, but I can honestly say they're the most durable. Dependable and longest lasting tablets without the need for redundancy because you can TRUST their performance ALL the time!
    Whether I'm flying into Katmai, hosting a wedding or running front of house for Mötley Crüe, there's few tasks I've found the iPad doesn't have an extremely good use(s) for.

    The iPad Pro is different. Not for everyone but I've had mine for two months nearly six weeks with pencil and keyboard. While my Air 2 isn't going anywhere, nor are the personal mini iPads for the family, the new iPad Pro WILL replace a dozen working iPad 4s and iPad Air1s in the field.
    They're definitely THAT GOOD, without the gray carpet photo manipulation (I'm not sure you realize how ridiculous your comments make you sound. Seriously. Paid by Apple 'cause you used LightRoom to crop, maybe brighten, than 'publish' your product shot. Lol!)

    Good luck with the spiders in Mom's basement. Save some cash, you don't have to admit how much you love it, but plenty give you a 30 day window to exchange. Seriously, no need to come back and tell us how much you're enjoying it. Or, that mom said "No" ....'you absolutely cannot have one til you graduate middle school!'
    One. Or the other.
  • Billie Boyd - Friday, November 27, 2015 - link

    The iPad Pro is nowhere close to the top tablets in my opinion, and just see rankings like - they don't rank it well either
  • akdj - Tuesday, December 29, 2015 - link

    Who in the hell is
    That was a helluva reach!
    Please realize the iPP, it's a different animal and more like the hybrid, 2 in 1 and whatever you want to call the PC versions of tablet/laptop portables. It'll never sell en masse like the iPad Air, iPhone or even the iMac. ....Yet
    My mother played with mine over Christmas and told my dad she'd prefer the iPad Pro to their new 5K iMac (27") as it "does everything I need it to, Joe! And it's got a pencil! Look what I can do with the photos!!!"
    IMHO, the world will look a lot different in the next couple of years computationally. Many are finding their iPhone 6s, Galaxy S6 Edge, Note 5, G4 or their iPhone 5s, S5 ---- older flagship phones are nearly ALL they need for a computer! Most folks aren't subscribers like many of us to the CC Adobe suite, nor are they using PS or LR for picture processing. Try Snapseed and Pixelmator. Their social, email, productivity apps (MS suite fully available and functional --- even more so on the iPP imho --- as well, if you don't need MS, Apple's suite kicks ass!)
    Their games, pictures and videos - in fact it's a repository for ALL media these days.
    Don't go looking for tertiary blogs rating tablets. Especially those without experience with said tablets (iPP isn't yet available in mass order, nor the pencils or keyboards), as reading your link it makes me wonder if he's used ANY of them or using a selection of his/her favorite sites in aggregate to make his own holiday list for 2015!
  • gw74 - Thursday, November 12, 2015 - link

    I'm more hyped about the review than the thing!
  • akdj - Tuesday, December 29, 2015 - link

    I'm with you gw74. In fact, it's the reason I came to comments.

    Simply to ask Ryan and crew when their 'full review' of the iPP will be available. I know with mine daily I find a new use, and I've not put mine down since purchase. I love it, starting to feel bad for my MacBook Pro, as it's getting less and less usage :(
  • zeeBomb - Wednesday, November 11, 2015 - link

    Hey, Ryan, do you think your team can do a review on the Meizu Pro 5? Just like your MX4 Pro review, I truly believe this device needs to be notice for using Samsung hardware + Apple Aesthetics.
  • leo_sk - Wednesday, November 11, 2015 - link

    The hardware is almost same as s6 so it would be more or less similar. Meizu mx5 would be more interesting since there has been no in depth review of Mediatek x10.
  • zeeBomb - Wednesday, November 11, 2015 - link

    True...but it still surprises me though how an underrated brand in China can make such beastly phones (not forgetting the AMAZING Audio chipsets inside) and make the user experience nothing short of impeccable.

    TBH, its all up to Andrei for this one.

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