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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  • Ppietra - Wednesday, October 6, 2021 - link

    process node differences cannot account for the degree of difference in efficiency. N6 to N5P would account for less than 30% reduction in power at the same clock speed (using same design).
    What we observe is a 60% reduction in energy vs the D1200 while achieving almost the same performance at a lower clock speed. Apple’s design has a better IPC while consuming much less. Even if we were to compensate for process node advantage we would still have around 40% reduction in energy consumption.
    Anyway, Andrei has mentioned that these power consumption values are also affected by other things, not just the CPU cores, so clearly Apple is doing a better job at keeping power under control.
  • Fulljack - Thursday, October 7, 2021 - link

    Snapdragon 888 are fabricated on Samsung 5nm LPE and NOT TSMC N5 (5nm)
  • erinadreno - Monday, October 4, 2021 - link

    Not exactly a fan of Apple's design choice of mobile phone SoC. Yes the performance is good, but no integrated modem, hence larger PCB and/or smaller battery. They basically trade area with performance. Due to the lack of peripherals and smaller screen, it's difficult to utilize the full potential while still burning the energy.

    The same design philosophy (M1) is a lot better on tablet and laptop where performance is less likely to be wasted.
  • melgross - Monday, October 4, 2021 - link

    That’s not an Apple design choice. That’s a Qualcomm limitation. Qualcomm won’t allow Apple (or anyone else) to integrate their modems on a chip not made by Qualcomm. Nevertheless, Apple’s overall phone designs are still more efficient.
  • michael2k - Monday, October 4, 2021 - link

    1) That's like complaining about Intel's lack of integrated NVIDIA GPU
    2) They increased the battery size year over year, so that claim is false
    3) They aren't trading area with performance, as indicated by their sandwich PCB, they're trading heat dissipation for reduced performance; the heat dissipation of the CPU + GPU is what limits the performance, but that also probably also helps with increased battery life too
    4) Peripherals? WTF are you talking about
    5) Smaller screen? WTF? 5.4", 6.1", and 6.7" aren't generally smaller screens, especially when their performance is unrivaled, their battery life is good, and their energy efficiency is some of the best out there

    It's like you commented without even reading the article!
  • erinadreno - Tuesday, October 5, 2021 - link

    They increased battery size year over year, yet still beat by pretty much any other smartphone. The area means ASIC area and package size, Apple could step back their design with smaller die size and lower performance, like 1+3 CPU and 3 cluster GPU config for mobile. The sandwich PCB is the indication of trading area with performance. They just circumvent the area problem by having thermal issue. Peripherals are the hardware/software platform around the processor, OS, IO devices, etc. iPhone pretty much lack any real application (not apps) where this much processing power is needed, other than playing games for 5 minutes. I'd agree 6.7" is a large screen, but the other two are definitely small in today's market.
  • jospoortvliet - Tuesday, October 5, 2021 - link

    How are they beat by almost every other phone? Their battery life is in the absolute top. Sure they achieve that with a smaller battery and thus lower weight and size - to the benefit of their customers - but hey, that's what it means to be perf per watt leader.
  • markiz - Friday, October 15, 2021 - link

    Meh. iPhone never had good battery life. In fact, it was terrible for many years. And they had slow charging. Still do.
    That said, Galaxy S line also had until S21 poor battery life, about the same.
    But there are numerous other high/er end phones that fare much better. I guess in USA only iphone and galaxy matter so you look at it differently.

    It was also heavier slightly.
    e.g. iphone 11 194g, S20 163

    So there was no benefit to the customer in these regards.
  • cha0z_ - Tuesday, October 5, 2021 - link

    my 11 pro max already sh*ts on all top current android phones and 13 pro max sh*ts on my phone on top of all top current gen android phones. They do it with smaller battery? This is not a bad thing, will let you guess why by yourself.
  • markiz - Friday, October 15, 2021 - link

    Iphone 13 has worse battery life then S21.
    pro max 13 has slight advantage, but galaxy is a half step behind. Maybe they can do better with s22. It's not at all correct to say that it shits on them in this particular regard.

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