The Snapdragon 865 SoC: Beating Expectations

We’ve covered the Snapdragon 865 extensively over the last few months, and more recently did a performance preview of the chip on the Galaxy S20 Ultra:

It’s safe to say that Qualcomm managed to beat our expectations in terms of power efficiency improvements. Which is something we’ll go over in more detail in this piece as well.

At the heart of the Snapdragon 865 we find Arm’s newest Cortex-A77 CPU cores. The new microarchitecture is said to bring a 20-25% IPC improvement over its predecessors, and that’s where the new SoC derives most of its performance improvements from, as the clock frequencies of the cores are identical to that of last year’s Snapdragon 855.


Snapdragon 865 CPU Topology

One aspect where Qualcomm did improve the design is in doubling the shared L3 cache of the CPU cluster, going from 2MB to 4MB. Not only does this further improve the performance of the CPUs by allowing for more data to be cached on-chip, but Qualcomm has explained that one of the primary reasons for this was to also improve power efficiency of the SoC by reducing how often the SoC has to access the DRAM, which is a relatively power-expensive operation.

The chip still has a 3MB system level cache that serves the various IP blocks on the SoC – it’s again meant to not only improve performance but also improve power efficiency as it avoids external memory accesses. The memory subsystem here is smart and detects when to bypass this cache when there’s latency-sensitive workloads, and in general we’ll see some massive memory subsystem improvements on the part of the Snapdragon 865 in a later dedicated section.

All the CPUs being in the same cluster and cache hierarchy means that the core-to-core latencies are relatively uniform, only differing based on their frequencies and lower level cache access latencies. It’s not too much of an exciting metric here, but it’s important context to have as we’ll consider the Exynos 990’s CPU topology in just a bit.

Again, we’ve covered the Snapdragon 865 quite extensively in the above linked articles so I recommend reading them again for other details on other parts of the new chip, such as the new ISP, DSP, and GPU details. However, one aspect that’s very defining for the flagship Qualcomm chipset this year is that the company is separating the modem from the SoC – essentially making the SoC just an application processor for this generation.

The external nature of the X55 modem has a few implications: first of all, there’s an additional component on the motherboard which vendors will have to make space for, which means additional cost. Secondly, there’s the big question of how power efficiency will be affected by the external modem. We’ve seen Apple devices perform excellently over the years while never having an integrated modem, and I feel like the Snapdragon 865 and X55 also fall into this classification, as I haven’t seen any major differences in efficiency due to the external nature of the modem.

Design, Continued: An Ultra Mega Phone The Exynos 990 SoC: Last of Custom CPUs
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  • iphonebestgamephone - Sunday, April 5, 2020 - link

    Oh and what does a pro like you use? Reply
  • sanjeev.k - Saturday, April 4, 2020 - link

    Hi Andrei,
    Thanks for your detailed review. Any change Anandtech will be reviewing the note 20 later in the year (as Anandtech have not reviewed the note xx series past few years) ?

    Reliable leaker @IceUniverse hints that Note series will implement an optimised solution for 120 Hz refresh rate - so I am assuming that to mean that power inefficiency issues at 120 hz refresh rate will be fixed in the note series.
    If you are going to review the Note series, at least we will know whats the improvement like as compared to Galaxy S series. Then I can decide if I want to import the Snapdragon 865 Note series or import S20 865 series and bear with the 120 Hz power consumption issue
    Reply
  • abufrejoval - Saturday, April 4, 2020 - link

    I bought the first Galaxy Note for its size: My hands are much more capable than my eyes up close. I stuck around for the Note 3 and then abandoned the brand as they went off into Absurdistan with too much glass and metal replacing replaceable batteries (both Notes still work today with 2nd and 3rd sets of batteries).

    But I’ve always longed to see another feature become mainstream usable, that these Notes started, albeit with serious functional limitations: Desktop or docking mode.

    The Note 2 dock also worked with the Note 3 and it was the first that I tried to use for extra light business travel with a foldable BT keyboard even a BT mouse on an HDMI connected big screen. Mixed DPI support wasn’t quite up to snuff, even with custom ROMs that added Ethernet connectivity (security constraints mandated that in some cases).

    In terms of computing power everything since the 820 has been enough for me in mobile use: If I really want to crunch numbers, I use HPC servers which I access via SSH, RDP or VNC and gaming is much more fun with an RTX 2080ti.

    Phones as a VR headset replacement died far too quickly for my taste, my Le Max2 with its Le VR “luxury cardboard” companion still works pretty well, certainly for 3D movies.

    So, the only reason I would even remotely consider buying one of these overpowered smartphones is if they could do double-duty as mid-line laptop replacements. Unless Corona’ed I switch countries every week and taking a €1200 smartphone instead of a €1200 laptop along for the ride, while enjoying a 43”@4k desktop in both offices has a great appeal, especially since RAM (16GB), storage (500GB) and compute power are similar enough to satisfy me.

    I need both to handle the typical office/productivity stuff, surfing and the ability to access the big systems, be they compute farms or GeForce Now if I am in need for a monster kill. Yes, I love to be able to even run a Docker container in case I want to code something on the quick and up to chroot() that works pretty well with Android’s Linux kernel, even if it’s not quite as podman ready as the laptop.

    Last Samsung I got was a Tab S5e a month ago and its DEX qualities are really much improved. It has perhaps 25% of the power and capacity of these phones (at 50% price) but shows what could obviously be done here. Yet I see no mention of DEX on the S20 and I fear that Samsung’s product management is…

    The mere existence and perseverance of Exynos SoCs and rounded display edges prove that these people must be insane: Very sad, when you consider what the hardware could actually do!
    In the mean-time I am holding on to a very nice OnePlus 5 as daily driver, lovingly protected with a silicon sleeve that sports an elevated ridge around a flat display thus kept from drop’s harm with grip and buffer space. When I take it out for a bit of soap and water treatment, it looks like new.

    Chassis materials, colors, design, finger tip smudges? I couldn’t care less and the Note 1-3 removable plastic covers were plain perfect for longevity and flexibility.
    Reply
  • Rorange68 - Saturday, April 4, 2020 - link

    Great review.. somehow I haven’t seen these in the past but will watch for them now. Quick question... the chart on the first page shows all of the versions with dual sims.. a nano and esim. I was thinking of going for the Exynos because it’s been the only one listed as having dual sims but given the issues with 5g compatibility and the review you give it that seems like a really bad idea But if they all have dual sim it would make it a lot easier to leave my 10+ and get the 20+ or even splurge on the ultra on the chance they improve some of it via software updates. Reply
  • Rorange68 - Saturday, April 4, 2020 - link

    *5g comparability between for the Exxon’s version and US carriers Reply
  • MarcSant - Saturday, April 4, 2020 - link

    Outstanding! The Anandtech articles are simple the best, the definitive tech guide for all tech lovers. Keep up with the high level of these tech articles that in my opinion are the "must go" for all people that are interested in buy a gadget and see the "behind scenes" information that manufactures will not tell you. Reply
  • airdrifting - Saturday, April 4, 2020 - link

    No thanks on overpriced, never last, slow update, buggy software Korean garbage. Reply
  • surt - Saturday, April 4, 2020 - link

    Do they have a reputation for not lasting? I'm considering this for an upgrade from my Galaxy S6 which is still working fine but I'd like a better camera. Reply
  • airdrifting - Saturday, April 4, 2020 - link

    I haven't tried the newer ones, but I owned Galaxy S1, Galaxy S3, LG G2 and G3, none lasted 2 years (G2 being the best one imo.). I switched to Oneplus after that. Oneplus 3T lasted almost 3 years, now I am rocking a Oneplus 7 which I paid $400 for on eBay. Reply
  • shabby - Sunday, April 5, 2020 - link

    Lol how about you get a newer phone before bashing it. Reply

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