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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  • Taneli - Monday, May 25, 2015 - link

    GCN parts work well already, although this probably reduces the need for custom kexts. HD7850 on Yosemite here. Reply
  • dragonsqrrl - Saturday, May 23, 2015 - link

    "they could have got the same performance with 30% less heat and power with nvidia."

    Seeing how this is GCN 1.0, the gap is likely significantly larger than that.
    Reply
  • tabascosauz - Saturday, May 23, 2015 - link

    Be careful with that claim. Cape Verde is not the same animal as Tahiti and Hawaii.

    If I remember correctly, the HD 7750 was pretty competitive with the GTX 650 without the huge power consumption problem that is attributed to AMD nowadays. The HD 7770 was faster, but wasn't so far off of that.
    Reply
  • dragonsqrrl - Saturday, May 23, 2015 - link

    You seem to be getting power consumption and power efficiency confused a bit. A GPU can consume a lot of power and still be incredibly efficient. Likewise the opposite is also true, a GPU can consume little power but still be inefficient. Of course Cape Verde doesn't consume as much power as Tahiti or Hawaii in absolute terms, it also performs significantly lower. What's important is performance per W, and that won't change much with the M370X. Reply
  • MamiyaOtaru - Tuesday, May 26, 2015 - link

    I doubt he is. perf/watt was pretty damn nice with the 7750 series, at least at the time http://www.techpowerup.com/reviews/ASUS/HD_7750/27... Reply
  • dragonsqrrl - Tuesday, May 26, 2015 - link

    "at least at the time"
    Links article from over 3 years ago where the only competitive reference is Fermi...
    Reply
  • npz - Saturday, May 23, 2015 - link

    Until nvidia treats OpenCL as a first class citizen as it does CUDA and continues to provide good dev support, I think Apple will continue to prefer AMD gpus, all other factors being *roughly* equal (price, raw performance, thermals). Furthermore you're assuming they're the same when there's likely power management and thermal improvements in M370X, just like how all chip vendors make progressive improvements despite remaining on the same process size. Reply
  • npz - Saturday, May 23, 2015 - link

    edit: "... and AMD continues to provide good dev support" Reply
  • mmrezaie - Saturday, May 23, 2015 - link

    no AMD does not provide good dev support for OpenCL. They should be more active in HPC world. They are almost non existent. Reply
  • Taneli - Saturday, May 23, 2015 - link

    AMD doesn't have proper HPC interconnect, which is probably the most important and hardest part to do right in HPC. Nvidia has invested a lot to develop their their own solution. While it's true they should be more active in this segment, currently they don't have the resources. Reply

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