Battery Life: Good (60Hz) to Average (120Hz)

Last week we had published our initial battery life report on the S20 series, with some interesting findings. First of all, what needs to be mentioned again is that the new 120Hz display modes on the phones come with a quite large battery life impact. The behavior is exhibited on all our S20 models at hand and I think it’s likely due to the panel itself or the DDIC. Samsung had included various display refresh modes varying from 48, 60, 96 and 120Hz, however we have yet to find evidence of any mechanism that actively switches between the various modes. 

Device-On Black Screen Power Consumption (Airplane Mode)

As such, even on a black static screen, running at 120Hz comes with a quite steep power penalty that’s always present whenever the display is on, costing around 160mW of power.

I had noted that I found our variant of the Snapdragon 865 Galaxy S20 Ultra to have worse idle power than our Exynos phone version. Initially I had attributed this to possibly the SoC or even the nature of the external X55 modem, but since then I’ve also received an LG V60 and that device’s idle power is perfectly normal. The only other thing that differentiates our S20 Ultra here is the fact that it has the extra mmWave antennas and RF systems. It would be interesting to see if non-mmWave variants of the Snapdragon S20 Ultra behave any differently (Tip at our Chinese or Korean readers).

I also had made mention that the “Performance” mode of the Exynos S20 phones seemingly behaved quite overzealously in terms of its scheduling settings, and there was a quite drastic increase in power draw for what was not nearly an as drastic increase in performance. I’ve rerun the battery tests in the “Optimized” settings which doesn’t have the “Increased system speed” option enabled, and I’ve confirmed my suspicion as the battery life figures did improve by some notable amounts. I’ve also tested the Snapdragon in the “Optimized” setting and the runtimes only differed by 2% - for users having the Snapdragon versions it’s thus safe to simply leave that enabled.

Web Browsing Battery Life 2016 (WiFi)

In our web test, the new S20 series end up right about where you’d expect them to. The Snapdragon 865 Galaxy S20 Ultra at 60Hz fares the best amongst the tested models, and now represents Samsung’s longest lasting flagship device. Slightly behind it we find the Exynos S20 Ultra at 60Hz. The difference between the two phones here isn’t very big in this test, and I attribute this to the higher constant idle power draw of the Snapdragon phone which counteracts the much higher compute efficiency of the SoC. The Eyxnos S20+ ends up slightly behind the S10+ phones, but still lasts a good 12.65h in this test.

Once we turn on the 120Hz display modes, the battery life results on all the phones drops quite notably. The Snapdragon S20 Ultra goes from 14h to 11.3h, a 20% drop. The same applies to the Exynos S20 Ultra, with a 20% drop, but for some reason the S20+ sees a larger drop of 25%. In the systems performance section I did mention that there’s some software configuration differences between the Exynos S20 Ultra and S20+, maybe some of that plays part here in the results.

PCMark Work 2.0 - Battery Life

Overall, the conclusion on battery life isn’t quite as black & white as we thought it would be. The key point is to stay away from the seemingly broken Performance mode on the Exynos chipset and you’ll have roughly similar battery life results between the two SoC variants of the S20. Naturally, that’s only being achieved by the fact that the Exynos does showcase worse performance, saving energy by using the more efficient lower performance states more.

What’s valid for all variants of the phones is that the 120Hz display mode is quite the power hog. Samsung probably has the opportunity to improve this by introducing a better managed variable refresh rate mode that actually changes between the different refresh rates based on content, something that seemingly isn’t happening right now. Also switching to lower refresh rates when showcasing static content would be a huge power saver, but I’m not sure if Samsung would be able to actually deploy such a mechanism.

Display Measurement Camera Architecture: Huge New Sensors
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  • toyeboy89 - Friday, April 3, 2020 - link

    I'm really amazed in the fact that the iPhone XR is still beating snapdragon 865 in GFXBench in both peak and sustained performance. I am hoping the OnePlus 8 has better sustained performance. Reply
  • TMCThomas - Friday, April 3, 2020 - link

    Amazing review! Always wait for this one before getting a new samsung. And I won't be getting any of the s20 phones. For me the kind of feel like "beta" phones. The 120hz which is not quite ready for 1440p yet, the underutilized 108mp camera, the space zoom which is blurry, the camera hole still being there the big camera bump and so on. I think all these features and more could be way more refined with the next galaxy s which I'll be waiting for. Also the poor exynos 990 performance especially the GPU part is just unacceptable to me. Especially with it probably being a lot better next year, so I'll skip this year Reply
  • wheeliebin - Friday, April 3, 2020 - link

    Thanks Andrei, really good review!

    I have read many users complain about extra crazy post-processing on the S10/S20 series when there is a face detected in the frame. i.e. the phone will apply an aggressive 'smooth skin' filter that you can't disable unless you shoot RAW. I was hoping that your review might touch on this however there were no people in your example shots so perhaps you didn't get a chance to experience the problem. I wonder if you have heard of this issue and can replicate it yourself with the S20 range?
    Reply
  • anonomouse - Friday, April 3, 2020 - link

    Hi Andrei, did you also run the bandwidth and MLP sweeps from previous reviews? Last year you noted the Snapdragon 855/A76 had peculiar behavior in the L1, and it would be also interesting to see if there are any MLP changes in both the SD865 and the Exynos. Reply
  • anonomouse - Friday, April 3, 2020 - link

    Also, any idea why the new scores for these in 403.gcc seems to be worse than their previous generation products? In particular the score for the SD865 in these S20s is substantially worse than the SD865 score from the QRD preview article. Reply
  • Andrei Frumusanu - Saturday, April 4, 2020 - link

    Yes I know. I don't know why that happens. I also got a V60 now and the scores there are higher, I'm wondering if there's something with Samsungs shared libraries. Reply
  • anonomouse - Sunday, April 5, 2020 - link

    What type of compile flags are used for these binaries? Are they the same for all of the tested binaries (or even same binary on each given platform)? Are LTO or PGO used (and if not why not)?

    I'm also not convinced of this statement from the article:

    "I had mentioned that the 7LPP process is quite a wildcard in the comparisons here. Luckily, I’ve been able to get my hands on a Snapdragon 765G, another SoC that’s manufactured on Samsung’s EUV process. It’s also quite a nice comparison as we’re able to compare that chip’s performance A76 cores at 2.4GHz to the middle A76 cores of the Exynos 990 which run at 2.5GHz. Performance and power between the two chips here pretty much match each other, and a clearly worse than other TSMC A76-based SoCs, especially the Kirin 990’s. The only conclusion here is that Samsung’s 7LPP node is quite behind TSMC’s N7/N7P/N7+ nodes when it comes to power efficiency – anywhere from 20 to 30%."

    Both the energy consumed and the performance scores for both of these A76's seem to also very closely track the "mid" 2.43Ghz A76's on the TSMC-fabbed SD855 - all of which have similar L2's and similar frequencies, but possibly differ significantly (to the point of being suboptimal on latency) on the memory hierarchy and SoC beyond that - which greatly affects many of the SPEC workloads. All of these may also have implementation targets. Given this, is it really conclusive that the Samsung process is truly 20-30% worse in energy efficiency? Granted, things will probably not look pretty next year when TSMC is on a true 5nm and Samsung is not.
    Reply
  • Andrei Frumusanu - Monday, April 6, 2020 - link

    The test is just -Ofast without any other addition. LTO wasn't/isn't in a good state on the Android NDK - it's something to look into in maybe a new binary revision.

    As for the 855 figures, well, that's also on an earlier 7nm. HiSilicon did a lot better in terms of they physical implementation. If not against N7, 7LPP clearly has a disadvantage against N7P/N7+.
    Reply
  • Andrei Frumusanu - Saturday, April 4, 2020 - link

    I'll add them in, that test takes a whole day and I needed the phones doing battery tests and other stuff. Reply
  • dad_at - Saturday, April 4, 2020 - link

    Again, your S10+ Exynos results in pc mark are false as of 2020. In performance mode I easily get 9500 work 2.0 overall, about 9600 in browser bench, 21K in photo editing. PC mark in general is inconsistent, irrelevant benchmark, not representative of actual performance in daily usage. The same about these ancient SPEC synthetics. No one uses these for performance evaluation now. Reply

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