Thermal Throttling – Which SOC’s are the Worst Offenders?

The release this year of the new Snapdragon 810 has brought a new topic firmly in to the limelight, thermal throttling.

Thermal throttling is where the SOC will lower the frequencies of its CPU and GPU components and/or switch to a set of lower power cores in order to reduce heat, allowing the device to continue operating without burning a hole through your hand. 

The issue has become increasingly relevant in recent years as consumer’s appetites for thin devices grow and they get ever smaller and in the process, leave less room for heat to dissipate. Not only this but the growing need for more power in the palm of our hands requires pushing our devices harder for longer, 4K video and equally high resolution gaming being two of the biggest culprits.

To further complicate matters, the material used in the design of the device influences the thermal throttling so for example a device made of metal should be better at taking the heat away from the SOC allowing it to run at full speed for longer, but this is offset by the fact that this heat is transferred in to the hand of the user which is also unacceptable, so different materials can impact this throttling behaviour. See this great AnandTech article for more info on the topic: http://www.anandtech.com/show/7984/discussion-on-material-choices-in-mobile.

In summary, pushing our devices harder with less room to breathe means manufacturers are forced to throttle down performance when the heat gets too much and the end result is a reduction in performance. The Snapdragon 810 looked to be a particularly bad example of this which is the reason why it has attracted so much attention. A possible cause of this is that the 810 is built on a 20nm process and attempts to compete with the best SOC from Samsung, based on 16nm process, whilst sharing the same architecture, this means that to meet the same or similar performance the SOC will generate more heat and be forced to throttle more.

Today we're going to compare the throttling behaviour of a number of popular SOC's to see which are the worst offenders. To test this were going to look at peak, average and minimum performance recorded in a number of CPU and GPU benchmarks, with a larger discrepancy between the peak and minimum/average performance indicating more throttling behaviour.

The Devices

Device

Brand

SOC

iPhone 6 

Apple 

A8

Galaxy Note 4

Samsung

Exynos 5433

Galaxy S6

Samsung

Exynos 7420

Galaxy Note 4

Qualcomm 

Snapdragon 805

LG G4

Qualcomm 

Snapdragon 808

HTC M9

Qualcomm 

Snapdragon 810

ASUS Zenfone 2

Intel

Atom Z3580

We've picked a selection of the most modern flagship SOC's in use today to give a good representation of how your new device might perform. We'll certainly have our eye on the HTC M9 which has been picked out as a very bad example of thermal throttling, but is it deserved? Read on to find out...

CPU Performance degradation

To measure the reduction in CPU performance we looked at the worst, average and best performance as judged by Geekbench scores, the differences between these figures give a good ball-park indication of how badly throttling is affecting performance. 

First lets look at the disparity between the best and worst scores which give an indication of the 'worst case' scenario you can expect.

throttling-geekbench

Straight off we start to see why the HTC M9 has been called out for being overzealous with its thermal throttling and here we can see that the worst scores are some 65% lower than the maximum, suggesting a large and noticeable drop in performance. The Snapdragon 805 and new Snapdragon 808 are moderately better but still see a near 50% reduction in performance, even Samsung's best, the 7420, sees a large decrease despite its 14nm advantage. Impressively, the Apple A8 sees barely more than a 10% reduction suggesting very consistent performance. Intel's new Z3580 also puts in a good showing here.

Next up, let’s look at the average compared to the peak performance as this should give a better indication of real-world impact.

throttling-geekbench-avg

Again, its not a good sign for the Snapdragon 810 which is noticeably worse than the competition here, although the drop here is much less worrying than in the worst case scenario. What's most interesting here is that the Snapdragon 808, which didn't do that well in the worst-case scenario, performs very well here, only bested by the Apple A8 which scores impressively, giving near maximum performance on average. Taking in to account the drop in performance from peak, the Snapdragon 808 actually outperforms the Snapdragon 810 on single-core performance by around 200 points. Overall all SOC's aside from the Snapdragon 810 showed average scores that look to be quite reasonable and expected.

Overall then, the criticism towards the HTC M9 and Snapdragon 810 seems very much justified, with performance degradation that is considerably worse than competing SOC's, suggesting a genuine issue with its design. On average the other SOC's performed well, but worse-case performance is still an area for improvement for all bar Apple and Intel.

GPU Performance degradation

So, its not a great start for the Snapdragon 810 but can it redeem itself in the graphics tests?

throttling-gfxbench

The graphics scores bring some surprising results! Its worth noting firstly that there are big performance drops across the board for most SOC's here, more so than with the CPU scores. The Apple A8 is again leading the way with virtually no performance drop, it seems they can talk the talk and walk the walk, as consistent gaming performance was one of the key points they highlighted when launching the iPhone 6 - kudos to Apple here. 

In second place its another surprising result, the Snapdragon 808! It loses less than 5% of performance, a very impressive score. When compared to its bigger brother, the Snapdragon 810, the gap in GPU performance is closed significantly when looking at the average performance, such that there is only a 5% drop with the 808. The Snapdragon 810 is not the worst here, but still loses over 25% of its performance which is significant compared to what the A8 achieves. The Galaxy S6 doesn't do too well either, losing around 23%. Worst of all is the Snapdragon 805, possibly a result of trying to squeeze every last drop out of the ageing Krait architecture which Qualcomm has since abandoned for its flagship SOC's.

Summing it up

So what have we learned?

- Qualcomm dropped the ball with the 810, the criticism was justified and the figures show the Snapdragon 810 throttles performance significantly and for CPU throttling it is noticeably worse than the competition. For GPU it is only similarly bad.

Update: We've heard that Qualcomm have released a new Snapdragon 810 dubbed version 2.1 which is supposed to have reduced the throttling behaviour AND raised the GPU performance to Eynos 7420 levels. We'll cover this in another article soon, but it will certainly be impressive if true.

- Apple has done an amazing job of ensuring its cores provide high performance consistently, with very little degradation of CPU or GPU performance, this is an area the other manufacturers need to work on if they are to step out of Apple's shadow.

- Surprisingly, it is the GPU throttling that affects modern SOC's more than CPU throttling which is a worrying thing for mobile gamers, particularly as the marketing wars dictate a constant increase in screen resolution, burdening the GPU ever further.

- The Snapdragon 808 actually provides a very similar level of performance to the Snapdragon 810 when looking at an average level of performance and in worst case scenarios, may even be a better performer than the Snapdragon 810, this explains why LG and Sony decided to use the 808 over the 810 in their flagships.

Update: Sony decided to go with the Snapdragon 810 rather than the 808 for the Xperia Z3+/Z4; it didn't go well.

 


Post tags:

  • Apple A8
  • ASUS Zenfone 2
  • Exynos 5433
  • exynos 7420
  • Galaxy S6
  • HTC M9
  • Intel Atom Z3580
  • iPhone 6
  • Note 4
  • snapdragon 805
  • Snapdragon 808
  • Snapdragon 810
  • SOC
  • throttling

About the author

Jamie Englert has been writing about Android devices since he we was just a wee boy. Ok, that's a lie there were no Android devices back then but if there was he would have wrote about them. He is particularly excited about the growing wealth of awesome android mobiles coming from china and other eastern countries.

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  • Sujan More

    I don’t think any sony phone uses the 808.

    • http://www.mobiledroid.co.uk/ Jamie Englert

      You’re right buddy! There were rumours they were going to use the 808 in the Z3+/Z4 but it seems they went with the Snapdragon 810 instead. Judging by early reports, it might not have been a good choice: http://www.phonearena.com/news/Watch-Xperia-Z3-with-Snapdragon-801-outrun-the-throttled-Z4Z3-with-Snapdragon-810_id70532

      • Sujan More

        Yup,the sealed body design for waterproof doesn’t help it either.

        • Anton Zuykov

          that is irrelevant – cooling isn’t done by air anyways

      • theprov

        Hi, could you give us more information about the test, like number of bench’s runs, temperatures, ecc.ecc.

        • http://www.mobiledroid.co.uk/ Jamie Englert

          Its nothing too scientific, I just looked at the data in GFXbench and Geekbeench and took min, max and average scores across a sample of results.

    • vedran cupic

      LG G4 does

  • Will Tisdale

    So a dual core SoC emits less heat and therefore throttles less under load than a quad, hex or octo core device? I could have told you that’s how it would turn out – the results look as I’d expect them to if I had to guess.

    The A8 is a great SoC, yes, but it’s dual core. A direct comparison with an octo core 810 is unfair, even though I do think the 810 is a poorly designed SoC.

    The other manufacturers should quit focusing on the number of cores and instead focus on increasing the efficiency of cores, then they could reduce the core count to a reasonable level. An octo core CPU is pointless in a phone – it’s just marketing crap, it doesn’t benefit anyone – certainly not the users who end up with inconsistently performing devices because they are throttling too much.

    It’s quite an unscientific test, as the devices are from different manufacturers, the thermal throttling and clockspeed configuration is probably different on all of them, and they’re running different versions of Android with various skins, which makes direct comparison difficult and unreliable.

    The Snapdragon 808 has a practically identical GPU to the 805, but half the memory bandwidth, so that is quite likely why the GPU result turned out like it did, particularly with an offscreen test.

    • ImpassionedRule

      It’s the numbers that draws in the fanboys; “I hit x on Antutu suck it -insert company here-“.

    • rc1138

      Let’s just say: “Not all cores are similar. The whole big.LITTLE thing with a bunch of cores was made not so much for perfomance but for energy efficiency, because stock Cortex A15/a57 and probably a72 eat too much energy on high frequency. I still hope qualcomm will come back with their custom cores, right now even old krait based SoC are better than 810

  • Joakim Langkilde

    Nice

  • Mathias Cronqvist

    Jesus H. Christ man, proofread…

    • CyberAngel

      Ok…it’s “Jesus Christ”
      no “H. ” in the middle…

      • Mathias Cronqvist

        It’s an expression, dumbass. You do know Christ isn’t a last name either, right?

        • Crodley

          Sure there is an H in Jesus H. Christ. You know the prayer, “Our Father who art in heaven, Harold be thy name…”

          p.s. It’s a joke, I’m not serious…just in case.

          • Justin Foster

            Just N. Case ** for the sake of argument…

        • CyberAngel

          Well…you asked,
          you were served.
          I was hoping for a simple
          “Thank you!”

          • Mathias Cronqvist

            I didn’t ask anything, dumbass. Do you even know what a question is?

    • http://www.mobiledroid.co.uk/ Jamie Englert

      Yes it was pretty horrific actually, would you believe English is my first language? I’ve cleaned it up now. Thanks for the heads up!

  • Denys S

    Interesting article. I have never thought about how cpu/gpu overheating affects its performance. I used to have Nexus 4, which I only had for 3 weeks. I had to return it, because it was burning my face if I talked over it for more than 10 minutes.

    Also does 8-core snapdragon is fully utilized by Android OS? Does it really uses all 8 cores of the soc?

  • Feedback

    A well written article but … What does this tell us at all? Like Will Tisdale said: nothing.

    If the A8 would at maximum (with almost no throttle) perform worse then the QSD810 (throttling a lot) at maximum. Then the QSD810 would still be a better SoC.

    I’m not at all saying this is true, but if you care for writing an article, then write a good article instead, not something anybody can just think of. You could also consider costs and energy consumption and make the article even more interesting.

    • davidpro

      Do you know the difference in the single core performance of A8 n Snapdragon 810???

  • Robert Banu

    Snapdragon 810 is by far the worst and they still say there is nothing wrong with their SoC . They should be ashamed of themselves .

    Intel is the best after Apple in this regard . Pretty impressive !

  • JD

    I wonder how the 801 would fair. Apparently it was basically an 800 refined to the max.
    Also the A8 is a damn powerful chip so it’s very impressive that it’s not throttling that much, nice work Apple on the custom silicon.

  • Aditya Bhatt

    Qualcomm is becoming the AMD of Mobile Industry.

  • LD

    SOC’s are NOT offenders for Thermal Throttling – it is vendor decision how aggressive they want to run SoC. Samsung could have decided to run S6 more conservative even when cold, like Apple does with A8, which would result in lower overall performance but also in low difference between best and worst case.

    If you want to compare SoC’s , then compare their sustainable (worst case) performance in those phones. For example, Exynos 7420 geekbench score is 4864, while A8 is 2927. Now, if we assume those are ‘best’ scores (ie if geekbench is short benchmark rather than long one where mobiles would already throtle), and if we apply 40% throttling to 7420 and 10% throttling to A8, we get ‘worst’ case numbers for 7420 as 3425 geekbench score, and worst case for A8 as 2637 … meaning that 7420 is still 30% faster than A8 , within presumably same thermal range (ie range allowed in mobile phone)

    In short, it is HTC that is offender with SoC throttling, not Qualcomm. Qualcomm is ‘merely’ offender for creating underperforming SoC.

    • Anton Zuykov

      “For example, Exynos 7420 geekbench score is 4864, while A8 is 2927.”

      1. Considering the fact that geekbench test lasts about 20-40 seconds, it is nowhere near a sustainable result.
      SImilarly done test for 20-30 minutes might give a completely different picture.
      2. Exynos 7420 is Q2 2015 chip, hence you need to compare it to A9 which is Q3 2015. A8 is Q3 2014, buddy so I am not sure what you are trying to accomplish here by comparing this year’s chips with last year’s one.