Earlier this week Apple announced their 2015 15” Retina MacBook Pro. Though Apple didn’t make any CPU changes, they did make some GPU changes on the high-end model, swapping out NVIDIA’s GeForce GT 750M for AMD’s Radeon R9 M370X. Since the M370X was not a published part number in AMD’s recently-announced 2015 Radeon M300 series refresh lineup, there have been some questions over just what M370X really is.

At the time of the rMBP’s launch, we suspected that it was an AMD Cape Verde GPU, based on the fact that this GPU is also in the M375, which is the next part above M370X. With the new laptop shipping immediately, M370X models have already begun arriving in buyers’ hands, finally giving us a chance to confirm the GPU inside.


Image courtesy Reddit user ootan

Thanks to Reddit user ootan, who posted a screenshot of the rMBP’s System Profiler, we can now confirm that the GPU in the rMBP is in fact AMD’s Cape Verde GPU. AMD has previously used the 6821 device ID on other mobile Cape Verde parts, so 6821 is already a known quantity.

AMD M300 Series GPU Specification Comparison
  R9 M375 R9 M370X (rMBP) R7 M360
Was Variant of R9 M270/M260 Variant of R9 M270X Variant of R7 M270/M260
Stream Processors 640 640 384
Texture Units 40 40 24
ROPs 16 16 4?
Boost Clock <=1015MHz 800MHz <=1015MHz
Memory Clock 2.2GHz DDR3 4.5GHz GDDR5 2GHz DDR3
Memory Bus Width 128-bit 128-bit 64-bit
VRAM <=4GB 2GB <=4GB
GPU Cape Verde Cape Verde Oland/Topaz
Manufacturing Process TSMC 28nm TSMC 28nm TSMC 28nm
Architecture GCN 1.0 GCN 1.0 GCN 1.0

As for Cape Verde itself, as our regular readers may already know, it’s one of AMD’s first-generation GCN 1.0 GPUs, launched back in 2012. Compared to the GK107 GPU found in the GT 750M, it is a larger, more powerful (and at least in the desktop, more power-hungry) GPU, designed for more powerful devices than GK107 was. As for why Apple opted to switch now and to this GPU, we’ll leave that to Apple, AMD, and NVIDIA, though it’s by no means surprising that after having run GK107 for a couple of years, they would want to upgrade to a more powerful GPU.

Meanwhile, though we don’t have M370X on-hand at the moment, at least in the desktop, where GPU performance is unrestricted by thermals, Cape Verde fares very well. The rMBP on the other hand does have thermal constraints to deal with, so performance won’t be the same, but I expect it to fare reasonably well as well. Though at the same time I’m also curious if the use of a higher performance part has impacted the rMBP’s battery life when the dGPU is active; AMD and NVIDIA both do heavy binning, so a simple extrapolation won’t work here.

Update: And no sooner do I post this then someone sends me a screenshot of GPU-Z from a 15" rMBP running Boot Camp.

GPU-Z, for those unfamiliar with it, uses register poking to identify GPUs, so if the device ID wasn't enough, this settles it. This also confirms the clockspeeds - 800MHz core, 4.5GHz VRAM - and that the M370X is using GDDR5, unlike it's M375 counterpart. Thank you DMDrew812.

Source: Reddit User ootan (via SH SOTN)

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  • tipoo - Saturday, May 23, 2015 - link

    I guess the rationale is that you'd use the Iris Pro when you wanted to sip power, so they could go with a less efficient part...Still, I'm not sure that's a great gambit, as even my 15" with only the Iris Pro hits 99C regularly, so they'll probably hit the thermal wall with this thing as inefficient as it is. Reply
  • WorldWithoutMadness - Saturday, May 23, 2015 - link

    Don't worry. They will go with the old modus operandi.
    After a few years, they will recall the product because of overheating bla2.
    After a few years, that gpu would be practically cheaper and they will get a headliner for service.
    Reply
  • KikassAssassin - Saturday, May 23, 2015 - link

    It may not be a huge issue in OSX because it does automatic graphics switching, so the dGPU is only turned on when it's needed.

    Unfortunately, Bootcamp doesn't support graphics switching in Windows, and if you have a Mac with multiple GPUs, Bootcamp only reveals the more powerful one to Windows. As far as Windows is concerned, the MBP with a dGPU doesn't even have an iGPU, and that Radeon is going to be running 100% of the time which will have a big impact on battery life.

    If you want to run Windows on your MBP, I'd probably avoid this model if battery life matters at all to you.
    Reply
  • Meaker10 - Saturday, May 23, 2015 - link

    Idle power usage is a lot different to load power usage. Reply
  • Alexvrb - Saturday, May 23, 2015 - link

    As Meaker pointed out already, idle power on this chip is extremely low. Reply
  • MrCommunistGen - Saturday, May 23, 2015 - link

    Ugh... I hope these are at least REALLY well binned chips. Reply
  • jeffkibuule - Saturday, May 23, 2015 - link

    Really hoping we get 14nm FinFET GPUs next year. 28nm is pretty long in the tooth now. Reply
  • kspirit - Saturday, May 23, 2015 - link

    Wow. I didn't expect Apple to do something this messy with their highest end device... Reply
  • beginner99 - Saturday, May 23, 2015 - link

    Yeah strange. But then Apple fans are mostly not know for their knowledge about hardware so they can easily get away with it. Reply
  • odedia - Saturday, May 23, 2015 - link

    Question: I will be getting a 15" high end from work. The order was placed right at the crossover point between models. Which model would should I be "hoping" for? The new one or the nvidia one? Reply

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