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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  • eastcoast_pete - Wednesday, February 6, 2019 - link

    Interesting point. I don't know enough about the details of Apple's OLED displays on the XS and the Max, but, if you're right, it also means that Apple's claimed pixel density is slightly dishonest, or at least in need of a footnote. Now, regardless of density, the XS and Max have a very good looking and crisp display, as they should at those prices.
  • mkozakewich - Thursday, February 7, 2019 - link

    That's a good assessment. I find I like the pentile arrangement more, but only if it's got the same base density as an rgb stripe. The crops of the XS and XR show how similar they are except for the subpixel layout.
  • Ananke - Tuesday, February 5, 2019 - link

    When I compare my iPhone8 display to my Galaxy 8 or 9 displays - the difference is huge. iPhone XR has the same 720p display. It is not bad, but definitely less sharp and less colorful then Samsungs, and definitely not worth $750. The XR would've been a perfect buy around $400, or free-$100 per line after contract, but indeed I agree with the previous comment - Apple created it just to have something that doesn't jeopardize its XS sales. Apple simply wants average sale price to be above the $1000 mark, and that's it. Simple. We all saw how it worked for them on Wall Street though :) :)
  • uhuznaa - Tuesday, February 5, 2019 - link

    Absolutely, yes. Apple could have used a higher resolution display and made the battery a bit smaller to arrive at the same or even less thickness as the XS (-0.6 mm), but then fewer people would buy the more expensive iPhones with a better margin for Apple. They're fully in the zero-sum mindset now, which is a natural consequence of trying to maximize profits instead of market share.
  • jakoh - Tuesday, February 5, 2019 - link

    Maximizing profits can sometime start to bite you.
    Apple phones are so expensive.
    I understand that Samsung phones are expensive too. But often you can get a note 9 for $750-799. When can you say that about iPhone Xs or Xs max?
  • mrochester - Tuesday, February 5, 2019 - link

    Probably in a couple of years time.
  • cha0z_ - Monday, February 11, 2019 - link

    I got my note 9 on contract from my carrier for half the price that I would had given for iphone xs max from the carrier too. I literally could had taken 2 note 9 phones instead of one iphone. No carrier sub for iphones and this creates insane price differences, then I would have to buy a new charger as the one in the box is insanely slow and headphone adapter. Even if we agree that the xs max is a better phone (tho this can be debated as some things that the note 9 can do, the iphone can't) - it's not that much better to spend twice the money on it, but each on it's own for that one.
  • lightsout565 - Tuesday, February 5, 2019 - link

    "I think the main issue I have with the iPhone XR’s display is that it’s actually somewhat of a downgrade from the iPhone 8 and 8 Plus in terms of resolution – while I understand that Apple wanted to use a more affordable panel, I do think it would have prudent to at least match the 401ppi pixel density of an iPhone 8 Plus."

    It's only a downgrade when compared to the 8 Plus. The XR and the 8 have the same PPI so this wording is a little misleading.

    Also, when comparing the 100% crop of the XS and XR, the main noticeable difference as you say was the clock icon numbers. This text is at a point size that no-one would realistically be reading in practice. I'd be more interested in 100% crops of the the icon label text, the text in a message/email, etc. I'm curious how the sharpness holds up on larger system fonts at a point size you'd realistically be reading.
  • tipoo - Tuesday, February 5, 2019 - link

    I have a 7 at the same 326PPI and I easily see some graininess around text at any size fwiw. Same with the curves on icons and notification dots.
  • jell0king - Tuesday, February 5, 2019 - link

    After owning an XR and returning it to get a year old X I have to agree with your assessment of the design of the phone: It's just to thick.

    The thickness of the phone is immediately noticeable and i hadn't even put a case on it yet. The X/XS/XS Max are infinitely more comfortable to hold for extended periods of time. Why I haven't seen this mentioned in other reviews is mind boggling but for me the phone was very uncomfortable to hold.

    I could live with the low res screen and thick bezels, loved the battery life and I enjoy the 'fun' colors...but that thickness was just a deal-breaker.

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