5nm / 5LPE: What do we know?

Starting off with the biggest new change of this generation, both the Snapdragon 888 and the Exynos 2100 are manufactured on Samsung’s new 5nm process node, which is the biggest unknown in today’s comparison.

What’s important to remember is that although Samsung calls this node 5nm, its design and characteristics are more similar to that of their 7nm node. Key new characteristics of the new node here are the reintroduction of single diffusion breaks (SDB) on an EUV process node, as well as slight changes in the cell libraries of the process.

Advertised PPA Improvements of New Process Technologies
Data announced by companies during conference calls, press briefings and in press releases
  7LPP
vs 10LPE
6LPP
vs 7LPP
5LPE
vs 7LPP
3GAE
vs 7LPP
Power 50% lower 20% 50%
Performance 20% ? 10% 35%
Area Reduction 40% ~9% <20% 40%

Per Samsung’s own numbers, the foundry claims that 5LPE is either 20% lower power than 7LPP, or 10% more performance. These are actually quite important figures to put into context, particularly when we’re comparing designs which are manufactured on TSMC’s process nodes.

In least year’s review of the Galaxy S20 series and the Exynos 990 and Snapdragon 865 SoCs, an important data-point that put things into context was Qualcomm’s Snapdragon 765 SoC which was also manufactured on Samsung’s 7LPP node, and featuring Cortex-A76 cores. In that comparison we saw that The Exynos 990 and the Snapdragon 765’s A76 cores behaves very similarly in terms of power consumption, however they fell behind TSMC-based Cortex-A76 cores by anywhere from 20% to 30%.

In that context, Samsung’s 5LPE process node improving power by 20% would mean they’d only be catching up with TSMC’s 7nm nodes.

Cortex A55 @ 1.8GHz - SPEC2006 456.hmmer Power

An interesting comparison to make – and probably one of the rare ones we’re actually able to achieve today, is the comparison between the Cortex-A55 cores inside of both the Snapdragon 865 and the new Snapdragon 888. Both SoCs feature the same IP cores, clock them at the same 1.8GHz frequency, and both feature the same amount of L2 cache, with their only real difference being their process nodes.

Using SPEC’s 456.hmmer – because it’s a workload that primarily resides in the lower cache hierarchies and thus, we avoid any impact of the possibly different memory subsystem, we can see that both SoCs’ power consumption indeed is almost identical, with performance also being identical with a score of 6.84 versus 6.81 in favour of the new Snapdragon 888.

So at least at first glance, our theory that Samsung’s 5LPE merely just catches up with the power consumption and power efficiency of TSMC’s N7/N7P nodes seems to be valid – at least at these frequencies.

Further interesting data is the voltage curves of the CPUs on the Exynos 2100. I’ve extracted the frequency voltages tables of both my devices, a regular S21 and an S21 Ultra, with the above curves being the better binned chip inside of the smaller S21.

Generationally, Samsung seems to have been able to greatly reduce voltages this generation. On the Cortex-A55 cores, the cores now only require 800mV at 2GHz whilst the Exynos 990 last year in our review unit they required over 1050mV. Similarly, although the comparison isn’t apples-to-apples, the Cortex-A78 cores at 2.5GHz only require 862mV, while the Cortex-A76 cores of the previous generation required also 1050mV.

What’s also very interesting to see is the voltage curves of the Cortex-X1 cores versus the Cortex-A78 cores: they’re both nigh identical to each other, which actually lines up with Arm’s claims that the new X1 cores have the same frequency capabilities as the A78 cores, only being larger and increasing their power consumption linearly in relation to their frequency.

Samsung’s frequency tables indicate that they had been testing the A55 up to 2.6GHz, and the X1 and A78 cores up to 3.2GHz – however voltages here are quite higher and it’s also likely SLSI wouldn’t have been able to achieve similar chip yields.

Unfortunately, I wasn’t able to extract data from my Snapdragon 888 S21 Ultra, so I can’t tell exactly where it falls in terms of voltages compared to the Exynos 2100. One thing I can confirm as being quite different between the two SoCs is that Samsung does actually give the Exynos 2100’s Cortex-X1 core its own dedicated voltage rail and PMIC regulator, while the Snapdragon 888 shares the same voltage rail across the X1 and A78 cores. In theory, that could mean that in more mixed-thread workloads, the Exynos has the opportunity to be more power efficiency than the Snapdragon 888.

Generally, the one thing I want people to take away here is that although Samsung calls this their 5nm node, it’s quite certain that it will not perform the same as TSMC’s 5nm node. Usually we don’t care about density all too much, however performance and power efficiency are critical aspects that effect the silicon and the end-products’ experiences.

The Snapdragon 888 & Exynos 2100 Memory Subsystem & Latency: Quite Different
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  • s.yu - Monday, February 8, 2021 - link

    :) I said it before that this makes more sense, because if it's not throttling after a while, that equals to being constantly artificially throttled.
    That said, these figures suggest far higher potential of the 865 should somebody be able to overclock it so that it boosts to >8W for a short while then throttles back.
    From ROGP3's figures last year I thought the 865 was already relatively inefficient, but compared to this generation, whatever happened none of the SoCs(not even the two on the TSMC node) are more efficient than 865. At least those who bought 865 should be satisfied.
    Even though Samsung's 5nm seems to have flopped, it's exactly where it should be according to performance predictions a couple years ago, so they're actually on track, just that the fact that this is a half node one year behind TSMC isn't reflected in its nomenclature.
    Reply
  • eastcoast_pete - Monday, February 8, 2021 - link

    Thanks Andrei! This kind of review is why I read AT.
    Your results also confirm my view that QC had good reasons to "launch" the 870 as the backup option to 888-based devices; judging by your findings, even a plain 865 (no +) device will be a very competitive device, and at a lower price point to boot.
    When you write up your full review, please also cover whether Samsung will guarantee at least three full generational OS updates for their S21 devices for the US also; apparently, they do so for Europe. The absence of such guarantees has turned me off from buying "flagship" Android phones in recent years, and if Samsung comes through on that also for the US, I might reconsider a Sammy for 2021. Thanks!
    Reply
  • eastcoast_pete - Monday, February 8, 2021 - link

    Forgot to add this: The significant power consumption of either SoC plus the pretty, but still power-hungry display makes me wonder about the battery capacity Samsung chose for the S21 Ultra. My own view is that once the phone is big and the weight is over 200 g, may as well go really big on the battery; so, this looks like a case for >= 6,000 mAh to me, and in both meanings of the word "case". Reply
  • Xerxesro - Monday, February 8, 2021 - link

    Would the efficiency matter much in the real world? If you use your phone for regular things (calls, chat, browsing, a few apps) the sustained performance and power consumption shouldn't matter much. The cpu & GPU are only stressed for short bursts, unlike benchmarks and games. The higher frequencies of the Exynos might even make the phone feel a bit snappier. I think... Reply
  • Andrei Frumusanu - Monday, February 8, 2021 - link

    I've added the web-browsing tests - they're lighter than PCMark on the SoC. In the case of the S21U, the display is extremely efficient so it's still good.

    The lower brightness you use your phone, or the more the SoC difference will appear, and the less battery life you'll experience.
    Reply
  • brucethemoose - Monday, February 8, 2021 - link

    Out of the box with a few extra apps, flagships do a ton of processing in the background. And browsing still depends on burst performance.

    If you zealously clean the phone (and like Andrei mentioned, use high brightness), then yeah, power draw from the screen, radios are a bigger factor.
    Reply
  • Wereweeb - Monday, February 8, 2021 - link

    In the latest episode of "Phone manufacturers trying to fit a laptop inside a tiny glass brick" Reply
  • tkSteveFOX - Monday, February 8, 2021 - link

    Forgot to credit Andrei, another sensational research. Put most reviews to shame.
    Well done!
    Reply
  • Kishoreshack - Monday, February 8, 2021 - link

    Andrei Reminds me of Brian Klug
    But Brian's level was something else
    Reply
  • IanCutress - Tuesday, February 9, 2021 - link

    People only remember the best bits. Reply

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