iPhone 6 Plus Graphics Performance Speculation

Discussion in 'iPhone' started by jk9357, Sep 11, 2014.

  1. jk9357 macrumors newbie

    Dec 23, 2011
    To me, there are quite a few sketchy aspects regarding the iPhone 6 Plus's graphics performance.

    If we think back to the iPhone 4, it had twice the amount of pixels as the iPhone 3GS had, hence, an approximately 100% increase in GPU performance was necessary to produce the same performance as the 3GS. The result was, that the GPU performance was generally good, but the difference was noticeable in some games like Modern Combat 2. It was even more prominent in the iPod touch 4G.

    When we look at the iPad 3rd Generation, the outcome of doubling the pixels went way worse. People don't really mention this a lot, but the graphics performance of the 3rd Gen was, at the end of the day, pretty bad. Power-wise, it was still an improvement over the previous generation (about 100%), but not high enough to power all the extra pixels, and the result was a decreased GPU performance. I suspect that this is the reason Apple released the 4th Generation iPad just half a year later.

    iPad 3rd Gen On-Screen Benchmarks:

    Source: AnandTech

    Fast forward to now, we have a similar situation with the iPhone 6 Plus.
    The iPhone 6 Plus has to render about 2.5 million pixels.
    The iPhone 6 has to render about 1.0 million pixels.
    The iPhone 5s has to render about 0.7 million pixels.

    This leaves the iPhone 6 Plus to render about 150% more pixels than the iPhone 6, or 350% more pixels than the 5s.


    Source: Apple Special Event
    Note that he is assuming a 1080p resolution, but the actual rendered size will be 1242p.

    Phil Schiller said that the GPU performance is 50% better than the A7 graphics performance.


    Source: Apple Special Event

    This gives the iPhone 6 roughly the same graphics performance as the 5s. However, according to my logic, the iPhone 6 Plus would need another 250% GPU performance increase to have the same performance as the iPhone 5s.
    The real life values will probably be much lower, as to be expected, but even halving that number still seems very high.

    Allegedly the A8 GPU has 6 cores (up from 4), so does anyone know if this significantly increases performance in a way that wouldn't have been factored into the 50% Schiller mentioned?

    If this was not enough work for the GPU, there is also the downscaling factor that needs to be taken into account, so every image rendered has to be downscaled using a multiplier of 0.9581, which doesn't sound like it requires absolutely no extra power.

    Note that this decreased GPU performance would still be negligible in common usage and would predominantly be revealed playing high performance games.

    I want to know, what is you guys' take on this? I'm by no means an expert and I just came up with this after some contemplating. Maybe my train of thought has some (lots?) flaws.

  2. ronm99 macrumors 6502

    Jan 13, 2012
    I am ordering a 6+, and I'm not worried about this in the least.

    The A8 CPU / GPU will be able to handle the pixels instantly under normal operation.

    For graphics intensive games, if you run at full 1920x1080, you will get a slower frame rate. However, the iPhone 6 has a scaling engine, so games can always run at a lower resolution to get the frame rate up if needed. And most games will be designed to work with at least the iPhone 5 up, and even at full resolution, the 6+ will beat the iPhone 5.

    It is also possible that the GPU on the 6+ is clocked higher (just speculation).
  3. jk9357 thread starter macrumors newbie

    Dec 23, 2011
    The games won't be able to run at a lower resolution simply because the iPhone 6/6 Plus have a scaling engine, the game developers would have to implement that.

    The purpose of the "desktop class scaling engine", as Apple described it, is to upscale existing @2x apps, not to downscale @3x to @2x.

    Which brings up the possibility that developers might adapt their games to the iPhone 6 plus which makes sense, since for example you could simply distribute particles like dust evenly across the screen instead of creating more particles. I still believe if you play an unoptimized game on the 5s and the 6 Plus, both at native resolution, the 5s will be played at more FPS. We'll have to see how strong this difference will be once the benchmarks come in.

    I agree with you on the aspect that, as I stated in the original post, with normal usage the difference will probably be negligible.

    It would make me very happy if the GPU was clocked higher, since if we look at the Note and the Galaxy for example, the Note has more power.


    Forgot to mention that obviously the scaling engine also scales everything that's @3x to ~@2.95x to fit on the 1080p display.
  4. ronm99 macrumors 6502

    Jan 13, 2012
    Maybe you are right. It is definitely true that what with the normal APIs you have no control over how things scale.

    However, I would be very surprised if the Metal APIs did not allow the game developers to work at the actual pixel level and to scale as needed. The normal APIs abstract away what the pixels are, but with "Metal", serious game developers can work at a much lower level and have much more control over how the pixels are rendered.
  5. b.stolk macrumors newbie

    Nov 11, 2008

    You are right about the GPU deficit for iPhone6plus.
    It has to render 3.77 times more pixels than an iPhone5S.

    Some of this is due to the large offscreen buffer of 2208x1242 that gets downsampled to the physical 1920x1080 device.

    There is just no way you can render almost 4 times the pixels with only 1.5 times the GPU performance.
    So framerates on iPhone6 plus will be low.

  6. Uberdoober macrumors member

    Sep 17, 2014
    One thing I don't ever ever see mentioned anywhere is that the current ipad retina's use an A7 chip and have amazingly beautiful games. Don't they push around the same amount of pixels as the 6+!?!? If so, why aren't we referring to their performance with all this stuff. Someone please correct me if I'm wrong because it's driving me nuts.
  7. Anti-Lucifer macrumors 6502a

    Mar 9, 2012
    It's all due to these ridiculous screen resolutions that aren't standard. But then apple's way of making things "their standard".
  8. Trebuin macrumors 65816


    Jun 3, 2008
    Central Cali
    I agree totally.

    The 6+ drives a damand on the gpu but I still haven't found much that demands it in a normal app. These jumps then to come a bit early with apple and drive the requirement to improve. Not a bad choice.
  9. rkuo macrumors 6502a

    Sep 25, 2010
    The iPad runs the lower performing A7 series, pushes more pixels, and no one is complaining too much about their performance. For general purpose use the A7 and A8 do the job well. Your analysis is perhaps correct on a percentage basis, but not when it comes to real world use.

    If we are talking about games than yes, bring on as much GPU as we can get.
  10. MinEderPlayz macrumors 6502a


    Aug 3, 2013
    Hamburg, Germany
    I think Apple could have said "up to 2x faster" but they opted not to BECAUSE they knew the performance was worse due to screen size. That's why you get up to 50% WITH the larger display.

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