GPU Performance

The A12 SoC in the iPhone XSs showcased some fantastic results with some extremely high scores. We expect the iPhone XR to perform just as well – the only unknown factor here is the thermal designs of the two phones.

The iPhone XR actually differs quite a lot in this regard to its XS siblings: The iPhone XS and XS Max employ a “sandwiched PCB” motherboard design, in which the SoC lies between two substrates. While I don’t have empirical data on this, I just have to assume that such a design is not helpful for actually dissipating heat away from the SoC to the body of the phone.


iPhone XS vs. iPhone XR PCBs (Images Courtesy iFixit)

The iPhone XR on the other hand employs more of a traditional single PCB design, such as found in past iPhone models. The SoC here is found inside an EM shield facing towards the screen assembly. I was always questioning this a design as well because theoretically there should be a slight air gap between it and the display backplane which could hinder heat transfer. Also because the SoC is facing towards the display, it also doesn’t make direct contact with the aluminium frame of the phone. As Apple’s SoC’s become ever more power hungry at their peak performance states, it is weird to see that Apple hasn’t been any more aggressive in their thermal dissipation solutions as say what we now commonly see from some higher-end Android counter-parts.

3DMark Sling Shot 3.1 Extreme Unlimited - Physics

Starting off with the physics subtest, which is mainly a CPU test within a (GPU) thermally constrained scenario, we see the iPhone XR perform nearly equally to the iPhone XS, showcasing some very good sustained performance near the peak levels of the SoC.

3DMark Sling Shot 3.1 Extreme Unlimited - Graphics 

The graphics subtest of 3DMark also doesn’t seem to drastically differ from the iPhone XS. This was one of the tests that caused problems for the XS variants as it would cause the phones to crash the GPU at peak performance, only able to complete the test when the phones were warmer and throttled more. I re-tested the XS and did manage to somehow complete a run at a higher peak performance state, however my iPhone XS Max still managed to crash with the same behaviour as back in October.

Moving onto the GFXBench suite, starting off with the two variants of the new Aztec sub-test, which represents a more modern 3D workloads:

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

The iPhone XR performed extremely well in these two tests, however we do note that there’s a difference in the peak performance showcased by the XR and the XS variants: It seems that Apple might be running the GPU at a slightly lower frequency here. This would match the slight difference in the peak 3DMark graphics score as well, and could be the reason why the iPhone XR didn’t crash in the same way the XS did.

GFXBench Manhattan 3.1 Off-screen GFXBench T-Rex 2.7 Off-screen

In the Manhattan 3.1 and T-Rex offscreen tests we see similar behaviour: the peak performance of the XR is slightly lower than that of the XS phones, however the sustained scores are higher.

One of the reason we use off-screen scores in our benchmark suite is that it allows for an apples-to-apples workload comparison across all devices. While in most cases this is a good and representative scenario for what you might expect from the thermals in actual games, this actually doesn’t seem to apply for the iPhone XR:

Because of the relatively low screen resolution on the part of the XR’s display – a sub-FHD 1792×828 – I’ve had a lot of trouble actually getting workloads to push the A12's GPU to its peak frequencies in on-screen scenarios. This causes an interesting dilemma for the iPhone XR: It has absolutely abundant GPU performance that won’t be used any-time soon. As game developers on iOS will be targeting and tuning their workloads to run smoothly on the most demanding devices of a generation, it means that games will most likely be setting their baseline as the higher-end iPhone XS Max, which has to push over twice the pixel resolution. The net result is that for any given 60fps graphics workload, the iPhone XR will run cooler and with a longer battery life than what you would experience on the XS or XS Max.

If gaming and gaming performance (and battery efficiency) is important for you, then the iPhone XR is definitely the phone to get. Not only does it deliver class-leading performance, but it also will be quite future proof in terms of performance thanks to the lower-resolution display.

System Performance Display Measurement
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  • Lolimaster - Thursday, February 07, 2019 - link

    The resolution is just craptastic vs a 5.8" S9 where you can have TRUE 1080p RGB AMOLED when going 1080p in the options down from 1440 pentile mode. Reply
  • darkich - Thursday, February 07, 2019 - link

    Wow, just wow.
    I find this comment to ironic because the only gripe I have with the XR is not the display not how ridiculously big bezels it has..as if it has a bumper case.
    That some people can't see this is beyond me..
    Reply
  • ss96 - Tuesday, February 05, 2019 - link

    Hi Ian, do you have a number for the display's contrast ratio? Interested to know how it compares to previous iPhone LCDs.
    Also, what happened to the charts comparing contrast, color accuracy to the competing smartphones? Really miss those.
    Reply
  • Andrei Frumusanu - Tuesday, February 05, 2019 - link

    https://images.anandtech.com/doci/13912/XR-greysca...

    1450 to 1550:1 to depending on brightness.

    As for the the accuracy charts, I think it lead to a lot of readers to too quickly jump to conclusions and misunderstand what the figures actually meant, and for example in the past we had some cases of phone A having a dE of say 2 vs a dE of 1 - in both cases the actual differences in this case are extremely small and in isolated conditions probably imperceptible. However because they had just looked up the chart they determined that phone B was that much better because the bar graphs were that much shorter. I think this was quite counter-productive to the analysis of some devices and something I wasn't that big of a fan of.
    Reply
  • ss96 - Tuesday, February 05, 2019 - link

    Hi Andrei, thanks for your answer. I liked those because it was easy to know what other devices scored without having to go to their respective review, but I understand that it may be misleading. Reply
  • MarcusMo - Wednesday, February 06, 2019 - link

    I get what you mean regarding the dE comparison charts, however removing them all together seems like the nuclear option.

    Having review sites such as anandtech calling out poor accuracy again and again is part of the reason we’re seeing manufacturers finally care about this metric. Shaming them on a public comparison chart is a much more effective means towards that end then burying the numbers in each individual review.

    A suggestion would be to include a cutoff line in the chart, declaring anything below this to be imperceptible to the human eye. That, and the Anandtech readerships ability to parse objective data (why we visit this site), should be enough to assuage any fears of misinterpretation.
    Reply
  • mkozakewich - Wednesday, February 06, 2019 - link

    You should turn those charts into some kind of logarithmic efficiency thing, where a dE of <=1 is 100% and a dE of 3 is 90%, or something like that. Reply
  • eastcoast_pete - Tuesday, February 05, 2019 - link

    @Andrei: Thanks for this review. I largely agree with your analysis, but have an addition to your interpretation of Apple going below Full HD for the XR's display. Yes, build costs may well have been a little bit lower, but my suspicion is that, had the XR had even just an FHD display (otherwise identical in specs to the current one), the value proposition for the XS and XS Max would have been even more doubtful than it already is. Not that the XR is, by any means, a cheap phone - $ 749 for the 64GB entry-level model is a lot of money. But, I believe that Apple's decision to go with a below-FHD display for the XR was mainly to make it just that little less attractive so enough people still go for the premium models. Reply
  • fasterquieter - Tuesday, February 05, 2019 - link

    I think the answer is much simpler. They determined years ago that 326ppi is sufficient as far as clarity goes. They have approaching a decade of software optimized for this 2X pixel count. Going slightly denser would have resulted in negligible image quality improvements and the need to downscale the image, like the Plus phones. That came with its own disadvantages. I think they made the right call. Reply
  • Zeross - Tuesday, February 05, 2019 - link

    I think that you're perfectly right and In my opinion, something often overlooked is that the X and XS OLED displays are higher resolution mostly to compensate for the PenTile subpixels arrangement : the 458ppi figure is only true for green subpixels. Red and blue subpixels have a 324 sppi definition. So basically Apple have determined years ago that ~320ppi is good enough and the X (XS) screen resolution was chosen to ensure that all subpixels achieve this number. Of course I have no insight knowledge and I may be completely wrong but it would be a weird coincidence if by pure luck, the red and blue sppi of its latest phones is almost exactly the same that the one chosen in 2010 for the first retina iPhone. Reply

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