GPU Performance - Great GPU, So-So Thermals Designs

The GPUs on the A15 iPhones are interesting, this is the first time that Apple has functionally segmented the GPU configurations on their SoCs within the iPhone device range, with the iPhone 13 mini and iPhone 13 receiving a 4-core GPU, similar to the A14 devices last year, while the 13 Pro and 13 Pro Max receive a 5-core variant of the SoC. It’s still the same SoC and silicon chip in both cases, just that Apple is disabling one GPU core on the non-Pro models, possibly for yield reasons?

Apple’s performance figures for the GPU were also a bit intriguing in that there weren’t any generational comparisons, just a “+30%” and “+50%” figure against the competition. I initially theorized to mean +10% and +28% against the A14, so let’s see if that pans out:

3DMark Wild Life Unlimited

In the 3DMark Wild Life test, we see the 5-core A15 leap the A15 by +30%, while the 4-core showcases a +14% improvement, so quite close to what we predicted. The peak performance here is essentially double that of the nearest competitor, so Apple is likely low-balling things again.

In terms of sustained performance, the new chips continue to showcase a large difference in what they achieve with a cold phone versus a heated phone, interestingly, the 4-core iPhone 13 lands a bit ahead of the 13 Pro here, more on this later.

Basemark GPU 1.2 - Medium 1440p - Off-Screen / Blit

In Basemark GPU, the 13 Pro lands in at +28% over the 12 Pro, with the 4-core iPhone 13 only being slightly slower. Again, the phones throttle hard, however still manage to land with sustained performances well above the peak performances of the competition.

GFXBench Aztec Ruins - High - Vulkan/Metal - Off-screen

In GFXBench Aztec High, the 13 Pro lands in at a massive +46% performance advantage over the 12 Pro, while the 13 showcases a +19% boost. These are numbers that are above the expectations – in terms of microarchitectural changes the new A15 GPU appears to adopt the same double FP32 throughput as on the M1 GPU, seemingly adding extra units alongside the existing FP32/double-rate FP16 ALUs. The increased 32MB SLC will also likely help a lot with GPU bandwidth and hit-rates, so these two changes seem to be the most obvious explanations for the massive increases.

In terms of power and efficiency, I’m also migrating away from tables to bubble charts to better represent the spatial positioning of the various SoCs.

I’d also like to note here that I had went ahead and re-measured the A13 and A14 phones in their peak performance states, showcasing larger power figures than the ones we’ve published in the past. Reason for this is the methodology where we’re only able to measure via input power of the phone, as we cannot dismantle our samples and are lacking PMIC fuelgauge access otherwise. The iPhone 13 figures here are generally hopefully correct as I measured other scenarios up to 9W, however there is still a bit of doubt on whether the phone is drawing from battery or not. The sustained power figures have a higher reliability.

As noted, the A15’s peak performance is massively better, but also appearing that the phone is improving the power draw slightly compared to the A14, meaning we see large efficiency improvements.

Both the 13 and 13 Pro throttle quite quickly after a few minutes of load, but generally at different power points. The 13 Pro with its 5-core GPU throttles down to around 3W, while the 13 goes to around 3.6W.

GFXBench Aztec Ruins - Normal - Vulkan/Metal - Off-screen

In Aztec Normal, we’re seeing similar relative positioning both in performance and efficiency. The iPhones 13 and 13 Pro are quite closer in performance than expected, due to different throttling levels.

GFXBench Manhattan 3.1 Off-screen

Finally, in Manhattan 3.1, the A15’s 5-core goes up +32%, while the 4-core goes up +18%. The sustained performance isn’t notably different between the two, and also represent smaller improvements over the iPhone 11 and 12 series.

Impressive GPU Performance, but quite limited thermals

Our results here showcase two sides of a coin: In terms of peak performance, the new A15 GPU is absolutely astonishing, and showcasing again improvements that are well above Apple’s marketing claims. The new GPU architecture, and possibly the new SLC allow for fantastic gains in performance, as well as efficiency.

What’s not so great, is the phone’s throttling. Particularly, we seem to be seeing quite reduced power levels on the iPhone 13 Pro, compared to the iPhone 13 as well as previous generation iPhones.

Source: 微机分WekiHome

The 13 Pro models this year come with a new PCB design, that’s even denser than what we’ve had on the previous generations, in order to facilitate the larger battery and new camera modules. What’s been extremely perplexing with Apple’s motherboard designs has been the fact that since they employed dual-layer “sandwich” PCBs, is that they’re packaging the SoC on the inside of the two soldered boards. This comes in contrast to other vendors such as Samsung, who also have adopted the “sandwich” PCB, but the SoC is located on the outer side of the assembly, making direct contact with the heat spreader and display mid-frame.

There are reports of the new iPhones throttling more under gaming and cellular connectivity – well, I’m sure that having the modem directly opposite the SoC inside the sandwich is a contributor to this situation. The iPhone 13 Pro showcasing lower sustained power levels may be tied to the new PCB design, and Apple’s overall iPhone thermal design is definitely amongst the worst out there, as it doesn’t do a good job of spreading the heat throughout the body of the phone, achieving a SoC thermal envelope that’s far smaller than the actual device thermal envelope.

No Apples to Apples in Gaming

In terms of general gaming performance, I’ll also want to make note of a few things – the new iPhones, even with their somewhat limited thermal capacity, are still vastly faster than give out a better gaming experience than competitive phones. Lately benchmarking actual games has been something that has risen in popularity, and generally, I’m all for that, however there are just some fundamental inconsistencies that make direct game comparisons not empirically viable to come to SoC conclusions.

Take Genshin Impact for example, unarguably the #1 AAA mobile game out there, and also one of the most performance demanding titles in the market right now, comparing the visual fidelity on a Galaxy S21 Ultra (Snapdragon 888), Mi 11 Ultra, and the iPhone 13 Pro Max:

Galaxy S21 Ultra - Snapdragon 888

Mi 11 Ultra - Snapdragon 888

Even though the S21 Ultra and the Mi 11 Ultra both feature the same SoC, they have very different characteristics in terms of thermals. The S21 Ultra generally sustains about 3.5W total device power under the same conditions, while the Mi 11 Ultra will hover between 5-6W, and a much hotter phone. The difference between the two not only exhibits itself in the performance of the game, but also in the visual fidelity, as the S21 Ultra is running much lower resolution due to the game having a dynamic resolution scaling (both phones had the exact same game settings).

iPhone 13 Pro Max - A15

The comparison between Android phones and iPhones gets even more complicated in that even with the same game setting, the iPhones still have slightly higher resolution, and visual effects that are just outright missing from the Android variant of the game. The visual fidelity of the game is just much higher on Apple’s devices due to the superior shading and features.

In general, this is one reason while I’m apprehensive of publishing real game benchmarks as it’s just a false comparison and can lead to misleading conclusions. We use specifically designed benchmarks to achieve a “ground truth” in terms of performance, especially in the context of SoCs, GPUs, and architectures.

The A15 continues to cement Apple’s dominance in mobile gaming. We’re looking forward to the next-gen competition, especially RDNA-powered Exynos phones next year, but so far it looks like Apple has an extremely comfortable lead to not have to worry much.

CPU ST Performance: Faster & More Efficient Conclusion & End Remarks
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  • haukionkannel - Monday, October 4, 2021 - link

    Well A14 was already very fast so making A15 more efficient was right call! IMHO
    I need longer battery life and if these changes give that. The better!
  • herozeros - Monday, October 4, 2021 - link

    Granted I’m coming from an Xs, but battery on my 13 pro is nothing short of incredible.
  • 13xforever - Monday, October 4, 2021 - link

    Same, upgraded from Xs to 13 Pro and now I charge once every two days on average, and Xs had amazing battery life compared to 6s before it as well, so let's hope the trend continues.
  • Kangal - Monday, October 4, 2021 - link

    I think ProMotion takes its toll, but the new (LTPO) display should be more efficient. And the previous 5G antenna has probably been improved for better reception and less power drain. Combine these with the efficiency gains from the CPU/GPU and it adds up. Then there's the noticeable increase in battery capacity.

    All in all, I'm expecting the iPhone 13 models to have slightly less battery life than their iPhone 11 and iPhone 12 devices... but do it all while being faster and using the display in 120Hz Mode. And when it comes to certain Apps, I think it will scale down to 60Hz or 30Hz or even 1Hz, and save plenty of power... which should see the iPhone 13 embarrass its siblings. These were my predictions during the announcement, before this article.

    But Andrei says he's got all the data, so we will see if my predictions/deductions were even remotely close in the coming week in the next article.
  • Trackster11230 - Monday, October 4, 2021 - link

    I'm expecting the battery life to be better than both. The LTPO and reduction in screen Hz should enable better battery savings (I'm assuming more time is spent at 10 Hz [the lowest; it can't do 1 Hz], than at 120 Hz).

    Either way, it's been a significant jump in battery life from my X.
  • markiz - Monday, October 11, 2021 - link

    Incredible compared to XS, or in general?
    Why do iPhones have such poor battery when put through a standardized workload, like e.g. gsmarena?
  • Wrs - Thursday, October 14, 2021 - link

    As GSMarena wrote in the iPhone 13 review, it's primarily because of low call/standby efficiency. That's understandable because the cellular chip is discrete; most the comparison phones have it integrated and some stick to LTE only. Inasmuch as 89h for the normal 13 is over 3 days and nothing to complain of, their modeling for 1 hour each of calls, web surfing, and video each day is also a tad unrealistic for many. With more active use on wifi the battery life becomes way more competitive
  • michael2k - Friday, October 15, 2021 - link

    Anandtech's standardized workload disagrees with you:
    iPhone 13 Pro from 2021: 16.62
    iPhone 11 Pro from 2019: 13.33 hours
    Xiaomi Mi 10 Pro 2020: 12.96 hours
    iPhone 12 Pro from 2021: 12.95 hours
    iPhone XR from 2018: 12.95 hours
    Galaxy S21 from 2021: 12.86 hours
    iPhone 12 from 2020: 12.53 hours
    Xiaomi Mi 11 Ultra 2021: 11.70
    Xiaomi Mi 11 2020: 11.63 hours
  • deil - Monday, October 4, 2021 - link

    I am still not happy about their battery life, as andro phones get 150% more even on cheap devices.
    when they give you 3500 mah, and ando can get up to 18000 mah, something needs to be said.

    Interesting result from S21U, 2.9W for 75 frames, seems like very good result, is it locked by something ? that chip can go just as high as a15 can, wattage-wise, what's happened there ?
  • Stuka87 - Monday, October 4, 2021 - link

    Deil, not sure where you saw a phone with an 18,000mAh battery, it would have to be the size of a tablet to get anywhere close to that big. Even the Galaxy Note, which is pretty large, has a 4000 mAh battery. iPhones consistently score well in battery life tests, even against Androids with much larger batteries.

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