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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  • repoman27 - Saturday, May 23, 2015 - link

    Apple tends to stick with a chassis design for at least 4-5 years. With the Macbook Pro (Retina, 15-inch) they pretty much locked themselves into a certain TDP range for the dGPU (I'd reckon around 40-50 W) with the current chassis and cooling solution. If you look at GK107 and Cape Verde alongside the Maxwell options, you'll see that NVIDIA doesn't really offer anything that hits the sweet spot as far as price and/or TDP are concerned:

    GM108 = 1.02b transistors, 79 mm^2
    GK107 = 1.27b transistors, 118 mm^2
    Cape Verde = 1.5b transistors, 123 mm^2
    GM107 = 1.87b transistors, 148 mm^2
    GM206 = 2.94b transistors, 227 mm^2

    That being said, I don't love that this is the 5th generation of MacBook Pro (Retina, 15-inch) to be based on Intel 22 nm CPUs paired with TSMC 28 nm GPUs. And if the rumor that Intel is shooting for a September-November 2015 launch window for Skylake-H is true, then it looks like they may have decided to cancel Broadwell-H entirely.
    Reply
  • testbug00 - Saturday, May 23, 2015 - link

    GM107 costs 20-25% more to make (depending on exact yields) or so. And uses less power. And is faster.

    Intel hasn't managed to make a chip over 150mm^2 on their 14nm process that is commercially buyable. Well, maybe some FPGA partner made a large one.... But, when you sell each chip for more than the wafer probably costs, yield doesn't matter nearly as much.
    Reply
  • repoman27 - Saturday, May 23, 2015 - link

    GM107 may well provide better performance per watt than Cape Verde or GK107, but AFAIK, the TDP is way higher. As in most online sources claim something like 75 W for the GTX 950M, vs. only 45 W for a Radeon HD 7870M, which the R9 M370X is essentially a rebadge of. This is in line with the type of scaling you'd expect given the transistor counts seeing as everything is on the same process anyway. Reply
  • testbug00 - Sunday, May 24, 2015 - link

    um, no. A fully enabled GM107 running at well over 1Ghz uses less power than a 640CU Cape Verde at 1Ghz.

    http://www.techpowerup.com/reviews/NVIDIA/GeForce_...

    The 7770 is @ 1Ghz, the 750ti running 980-1150Mhz, with the average being 1140 across all the games tested. And the 750ti is about 50% faster (7770 is ~66%... 100 divided by 66 == about 1.5)

    so, at an average of 1150Mhz, the chip draws 52 watts while gaming. IF you think they cannot easily bin and reduce clockspeeds to get under 45W, you're crazy :)
    Reply
  • tipoo - Sunday, May 24, 2015 - link

    Those have soft configurable TDPs. Reply
  • halo37253 - Sunday, May 24, 2015 - link

    Macbooks are not gaming machines. People don't buy them to play games on them. Pointless to chose a card based solely on gaming performance. They went with the better compute card, simple as that. Reply
  • loguerto - Saturday, May 23, 2015 - link

    Apple is very focused on opencl coding, the advantage GCN have on that side probably is why apple choosed AMD over nvidia. Reply
  • dm27 - Saturday, May 23, 2015 - link

    How then is this MacBook Pro capable of driving a 5k display (5120-by-2880 @ 60Hz)? Reply
  • repoman27 - Saturday, May 23, 2015 - link

    The same way the 27-inch iMacs and Mac Pros can: by using two cables and two Thunderbolt 2 ports. Reply
  • Pneumothorax - Saturday, May 23, 2015 - link

    This is pure CHEAPNESS and cynicism in Apple's part in putting a 3 year old outdated gpu in their most expensive laptop. The 950M easily does 30+% faster within the same power constraints as this chip. To add insult to injury, Apple could've dumped these chips in the 1st gen 2012 retina macbook.
    AMD must me giving these away for free.
    Reply

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