Apple has a lot of optimizations for Intel at the moment from the instruction set down to the motherboards and chipsets. A great example is all the work they do in undervolting mobile chips so they perform better (when the latest MBPs shipped with this disabled, everyone really complained). Re-writing all that software definitely has non-trivial R&D costs.
When making a new motherboard design, a ton of stuff simply gets reused and moved around. Switch to a different chipset and you start all over for a lot of stuff. Even if AMD were 10-20% faster overall, their current "fast enough" Intel chips would still win out.
AMD's zen+ 3000 mobile chips don't compete with Intel in single-clock performance, clockspeeds, or total power draw. With the exception of the mac pro, Apple's entire lineup uses mobile processors. In addition, Intel probably gives amazing discounts to Apple. Zen serves them best as a way to squeeze out an even better deal.
A final consideration is ARM. Given the performance characteristics of A12, Apple most certainly has their sights set on using some variant in their laptops in the not-too-distant future. They already run their phone chips in their macbooks as the T2 chip. They are probably working on the timing to allow those chips to run more than the touchbar and IO.
> With the exception of the mac pro, Apple's entire lineup uses mobile processors.
In fact their entire desktop lineup now uses desktop-grade CPUs. (except possibly some entry-level iMacs that weren't subject to the recent refresh)
* iMac Pro: Workstation processor (Xeon)
* iMac 27": Socketed desktop processor (e.g. Core i9-9900KF in top config)
* iMac 21": Socketed desktop processor (e.g. Core i7-8700)
* Mac Mini: Soldered embedded desktop processor (e.g. Core i7-8700B)An i9-9900K has a 95w TDP, but Anandtech puts the real load number at around 170w TDP. I've seen people undervolt these down to around 110-120w in the 4.7GHz range. I imagine Apple's dynamic undervolting and custom motherboard can shave 10% or so off that total while their dynamic undervolting can go much lower with fewer cores and lower frequencies. While even that isn't going to make their tiny cooler keep sustained loads from throttling, it could get much closer.
In c't magazine's review of the current iMac, they found that the whole machine appears to have a power limit which is shared by CPU and GPU, so yeah, Apple are definitely doing something fancy in that regard.
Likewise, I do agree that Apple is likely switching to ARM for mobile—but are there any ARM cores on anyone’s product roadmaps that could power a Mac Pro, or even an iMac? Nah.
I do agree with the greater point: Intel probably do have an exclusivity agreement with Apple right now, and so Apple sticking with them right now isn’t evidence of anything in particular.
But to me, it looks like a natural shift for Apple, in the near future, to adopt a hybrid strategy: if they can switch to ARM entirely for their highest-volume segment (laptops et al), then they’ll no longer need the benefits of having Intel as a locked-in high-volume chip supplier, and will thus free to choose anyone they like for the much-lower-volume segment (desktops/workstations) on a per-machine basis. That might be Intel, or AMD, at any given time. They won’t get such great deals from Intel, but in exchange they can play Intel and AMD off one-another, now that they’re in healthy competition again.
Intel is probably just as aware of what Apple has on its roadmap as Apple is aware of what’s on Intel’s roadmap, so I would expect, if anything, that they’re scrounging desperately around for a mobile architecture that’ll be competitive-enough with the nascent A13 to stave off that collapse of a partnership.
It's true that quite a few have had AMD GPUs, and they made the more difficult PowerPC to Intel switch back in 2006 with OS X 10.4. But it would be a significant effort to change a processor partnership more than a decade old. No Apple developers have anything but Intel in their machines; it's not just an item on a BOM.
Given that Apple almost certainly has a research lab maintaining machines running macOS on top of Apple’s own ARM chips, to watch for the inflection point where it becomes tenable to ship laptops running those chips; and thus, given that Apple already has a staff for that lab whose job is to quickly redo macOS’s uarch optimization for each new A[N] core as Apple pumps them out; it doesn’t seem like much of a stretch that those same people would do a uarch optimization pass every once in a while to answer the “can we use AMD chips on desktop yet?” question, does it?
Apple wouldn't care that AMD narrowly beat Intel for 1-2 chip generations either. They'd care about AMD's ability to produce chips at large enough volumes and keep the pace going forward.
They've been burnt by Motorola before and Intel now, to just jump on a short-term bandwagon.
If AMD manages to keep this up (and ramp up their production) for 5+ years, then they might have a chance with Apple. But again, Apple is more likely to go for their own ARM based chips in 5+ years...
I think there's no reason to bother switching to AMD if/when they plan on moving to their own ARM based CPU within the next few years.
Not talking down about prior motherboards, but the next run will have some very high end designs and features compared to prior gen Ryzen as well. I'm really looking forward to upgrading in September/October. Looking at a 3950X unless a more compelling TR option gets announced before then.
People are hypothesizing this to be true given that Apple is putting Intel rather than AMD chips in the Mac Pro, and Apple doesn’t usually make dumb purchasing decisions, but does sometimes have private access to product roadmaps.