The Samsung Galaxy S6 and S6 edge Review
by Joshua Ho on April 17, 2015 9:00 AM EST- Posted in
- Smartphones
- Samsung
- Mobile
- Galaxy S6
- Galaxy S6 Edge
Exynos 7420: First 14nm Silicon In A Smartphone
This generation more than any generation in recent memory has been a time of significant movement in the SoC space. We were aware of the Exynos 7420 well before it was announced in the Galaxy S6, but for the most part I expected to see Snapdragon 810 in at least a few variants of the Galaxy S6. It was a bit surprising to see Samsung drop Snapdragon SoCs completely this generation, and judging by the battery life of the Galaxy S6 it seems that Samsung had their reasons for doing this.
For those that are unfamiliar with the Exynos 7420, this SoC effectively represents the culmination of their efforts in semiconductor manufacturing and integrated circuit design. On the foundry side, Samsung is leveraging their vertical integration to make the first SoC on their 14nm LPE (Low Power Early) process, which seems to be solely for Systems LSI until they can no longer use all production capacity.
We previously mentioned that Samsung’s 14nm process in general will lack any significant die shrink due to almost unchanged metal interconnect pitch, but this assumption was in comparison to their 20nm LPM process from which the 14nm LPE process borrows its BEOL (back end of line) from. Opposite to what we thought, the Exynos 5433 was manufacturered on a 20LPE process which makes use of a quite larger metal layer. The result is that one can see a significant die shrink for the 7420 as it is, according to Chipworks, only 78mm² and a 44% reduction over the Exynos 5433's 113mm². This is considerable even when factoring in that the new SoC had two added GPU shader cores. Beyond the swap from a LPDDR3 memory controller to a LPDDR4 capable one, the only other at first noticeable major functional overhaul on the SoC seems to be that the dedicated HEVC decoder block has been removed and HEVC encoding and decoding capability has been merged into Samsung's MFC (Multi-Function Codec) media hardware acceleration block.
Galaxy S6 PCB with SoC and modem in view (Source: Chipworks)
The move from a planar to FinFET process is crucial. Although this is covered in more detail in previous articles, the short explanation is that planar processes suffer from increasing power leakage at smaller process nodes as the bulk of the silicon becomes relatively more massive than the gate that controls the flow of current. This causes decreased power efficiency as the power source of the transistor starts to act as a gate itself. FinFET solves this problem by attempting to isolate the transistor from the bulk of the silicon wafer, wrapping the gate around the channel of the transistor to ensure that it retains strong control over the flow of current compared to a planar transistor design.
The effective voltage drop allowed by the process can be substantial. We can have a look at some voltage excerpts of common frequencies available on both the Exynos 5433 and 7420:
| Exynos 5433 vs Exynos 7420 Supply Voltages | ||||||
| Exynos 5433 | Exynos 7420 | Difference | ||||
| A57 1.9GHz (ASV2) | 1287.50mV | 1056.25mV | -234.25mV | |||
| A57 1.9GHz (ASV9) | 1200.00mV | 975.00mV | -225.00mV | |||
| A57 1.9GHz (ASV15) | 1125.00mV | 912.50mV | -212.50mV | |||
| A57 800MHz (ASV2) | 950.00mV | 768.75mV | -181.25mV | |||
| A57 800MHz (ASV9) | 900.00mV | 687.50mV | -224.50mV | |||
| A57 800MHz (ASV15) | 900.00mV | 625.00mV | -275.00mV | |||
| A53 1.3GHz (ASV2) | 1200.00mV | 1037.50mV | -162.50mV | |||
| A53 1.3GHz (ASV9) | 1112.50mV | 950.00mV | -162.50mV | |||
| A53 1.3GHz (ASV15) | 1062.50mV | 900.00mV | -162.50mV | |||
| A53 400MHz (ASV2) | 862.00mV | 743.75mV | -118.25mV | |||
| A53 400MHz (ASV9) | 787.50mV | 656.25mV | -131.25mV | |||
| A53 400MHz (ASV15) | 750.00mV | 606.25mV | -143.75mV | |||
| GPU 700MHz (ASV2) | 1125.00mV | 881.25mV | -243.75mV | |||
| GPU 700MHz (ASV9) | 1050.00mV | 800.00mV | -250.00mV | |||
| GPU 700MHz (ASV15) | 1012.50mV | 750.00mV | -262.50mV | |||
| GPU 266MHz (ASV2) | 875.00mV | 750.00mV | -125.00mV | |||
| GPU 266MHz (ASV9) | 800.00mV | 668.75mV | -131.25mV | |||
| GPU 266MHz (ASV15) | 762.50mV | 606.25mV | -156.25mV | |||
The ASV (Adaptive Scaling Voltage) numbers represent the different type of chip bins, a lower value representing a worse quality bin and a higher one a better quality one. Group 2 should be the lowest that is found in the wild, with group 15 representing the best possible bin and group 9 the median that should be found in most devices. As one can see in the table, we can achieve well up to -250mV voltage drop on some frequencies on the A57s and the GPU. As a reminder, power scales quadratically with voltage, so a drop from 1287.50mV to 1056.25mV as seen in the worst bin 1.9GHz A57 frequency should for example result in a considerable 33% drop in dynamic power. The Exynos 7420 uses this headroom to go slightly higher in clocks compared to the 5433 - but we expect the end power to still be quite lower than what we've seen on the Note 4.
On the design side, Systems LSI has also done a great deal to differentiate the Exynos 7420 from the 5433. Although the CPU architectures are shared, the A53 cluster is now clocked at 1.5 GHz instead of 1.3 GHz, and the A57 cluster at 2.1 GHz rather than 1.9 GHz. The memory controller is new and supports LPDDR4 running at 1555MHz. This means that the Galaxy S6 has almost double the theoretical memory bandwidth when compared to the Galaxy Note 4 Exynos variant, as we get a boost up to 24.88GB/s over the 5433's 13.20GB/s. We still need to test this to see how these claims translate to practical performance in a deep dive article in the future, as effective bandwidth and latency can often vary depending on vendor's memory settings and SoC's bus architecture.
Outside of the memory controller, LSI has also updated the 7420 to use a more powerful Mali T760MP8 GPU. Although the Exynos 5433 had a Mali T760 GPU as well, it had two fewer shader cores which means that achieving a given level of performance requires higher clock speeds and higher voltages to overcome circuit delay. This new GPU is clocked a bit higher as well, at 772 MHz compared to the 700 MHz of the GPU in the Exynos 5433. We see the same two-stage maximum frequency scaling mechanism as discovered in our Note 4 Exynos review, with less ALU biased loads being limited to 700MHz as opposed to the 5433's 600MHz. There's also a suspicion that Samsung was ready to go higher to compete with other vendors though, as we can see evidence of an 852 MHz clock state that is unused. Unfortunately deeply testing this SoC isn’t possible at this time as doing so would require disassembling the phone.
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Andrei Frumusanu - Friday, April 17, 2015 - link
Math is hard, corrected, thank you.Arbie - Friday, April 17, 2015 - link
SD Police here: no microSD, no sale. The reasons have been hashed over endlessly but I know what I want.mayankleoboy1 - Friday, April 17, 2015 - link
Im very puzzled by the large differences between the stock browser and Chrome. They both are based on the Blink engine, and use V8 for JavaScript execution.This definitely points to "optimizations" done in the stock browser for these benchmarks.
Could you do some other benchmarks on the phones?
JoshHo - Friday, April 17, 2015 - link
Basemark OS II and PCMark use the internal WebView engine and the 7420 doesn't do nearly as poorly in those browsing benchmarks as it does on Chrome.It's likely that Samsung Mobile has some work to do when it comes to optimizing against Chrome.
lilmoe - Saturday, April 18, 2015 - link
Or, it's the other way around. Google needs to do a LOT of work of optimizing Chrome for the various hardware out there, especially the most popular ones.Chrome isn't getting the highest marks in optimization you know, especially on the desktop. I thought that was a well known and understood issue?
Bob-o - Saturday, April 18, 2015 - link
Can someone explain to me why an application needs to be optimized for certain hardware? Isn't it just using libraries for rendering (OGL, whatever), and those libs have already been optimized for the GPU? And the non-rendering part of the app should be byte-compiled appropriately?Back in the 1980's I used to optimize apps for certain hardware. . . in assembly code. What are they doing these days? And why is it necessary? Poor abstractions?
mayankleoboy1 - Sunday, April 19, 2015 - link
These optimizations are not for specific hardware, but for the specific BENCHMARK. They can easily tweak parameters inside the Javascript engine to give higher score on specific benchmarks like Octane and Kraken. These optimizations would negatively affect the common web JS workloads, but would give higher benchmark score.Google/Mozilla wouldnt do such shenanigans as they do not priortize for specific benchmark, unless it also improves general JS workloads
bji - Friday, April 17, 2015 - link
I have a big problem with the way their camera module juts out from the back of the device. I have a Galaxy S5 Active (my first smart phone) and the camera broke within about 2 months of ownership. I believe it's because it juts out and is a focal point of stresses as a result (pressure while in pocket, pressure when laid on a flat surface, etc), and the very weak glass they use to cover the lense is subject to breaking. I've read many comments from others that this happened to them, and it happened to me. Now the camera is useless.I could put a big ugly case on the thing to protect the camera, sure, but that's why I bought the Active - because I didn't want to put a case on my phone.
I see that Samsung continues with this horrid camera module design. I won't be buying another Samsung with this characteristic.
name99 - Friday, April 17, 2015 - link
I suspect Samsung would do well to copy Apple in one more respect --- making cases a big part of the user experience.Something that critics of the iPhone 6 (in particular the "slippery sides" and "too much sacrificed for thinness" don't seem to get is that, IMHO, Apple sees cases as a significant part of the iPhone experience. Which is why they provide their own --- expensive but very nice --- high end cases, and are willing to accept the inevitable leaks we see from case makers in advance of new products.
Once you accept that a case is part of the story
- the thinness makes more sense, because you're going to be adding a few mm via the case
- likewise the camera bulge, while less than ideal, is not such a big issue
- likewise complaints about the fragility of glass backs, etc.
Cases also allow for a dramatic level of customization without Apple having to stock a zillion SKUs. You could even argue that the aWatch band proliferation is Apple having learned from the size of the case market for iPhones and iPads, and arranging things so that they get the bulk of the high-end money that's available in this space.
Every other phone manufacturer is in a much weaker position than Apple because they don't have the massive range of cases available. But they could at least try to improve the situation by providing their own cases --- maybe at least a high end leather model, a low-end plastic model, and an "I'm paranoid I'm going to drop my phone" model. They should also call out the cases during the big press reveal of each phone (like Apple does) and ship some cases along with each review unit (not sure if Apple does this, but they should).
All of which makes the Edge, IMHO, even more of a gimmick (in spite of Samsung claiming they will no longer do gimmicks). You get a much more expensive manufacturing process to provide something whose real functionality could probably be provided with a few colored LEDs, and you dramatically reduce the design space available for cases.
Oh well. Stay tuned for the next Samsung model which (don't tell me, let me guess) will feature as its big new feature a haptic (don't call it Taptic!) engine and which, with any luck, will manage to ship in at least one country before the iPhone 6S, so that Samsung can claim (and have the true believers accept) that this was their plan all along, that they were in no way influenced by Apple's obvious [based on aWatch and MacBook] next big UI element.
akdj - Sunday, April 26, 2015 - link
Hi name99. Wish there was an up vote;). Well said. As an owner of the iPhone 6+ (& each iteration before it), I've 'finally' found the Apple iPhone case:). Lol. I bought some Platinum Incipio Pro kickstand crap, a really lame Spec case (& I love their laptop shells on my MBP) before I finally made a trip down to the Apple Store and picked up the simple, brown leather iPhone 'Apple' case (I don't remember it being expensive though, seems like 39, maybe 49 bucks? Seems like the standard pricing regardless of manufacturer out of the gate).I'm embarrassed to say since 2007, I've never had the Apple case. Always bought third party and typically Mophies starting with the iPhone 4/4s.
Sorry, TL/dr -- not in defense of Android OEM lack of third party peripherals as its true but this last year, 18 months has changed some. The S-View case specific to the 's' and 'note' brands are pretty sweet. I use one on my Note 4 and like the Apple cam/case combo the S-Case also protects the camera protrusion while adding even more functionality. It's magnet sensing for turn on/off by open/close and the small maybe 2" x 2" 'S-View' (small window on front) allows answering of calls, quick text/tweet/FB/email/whatever-u-set-up response capability, notifications and time (customize faces and information on clock), weather and 'maps', settings, and more. It's slick and it's protective.
But you're right. The Apple iOS cases kick ass. I own the 'smart' cases (not covers, they suck) on our iPads too. Be nice if they quit changing the dimensions ever so slightly each iteration ala iPhone. Usually get two generations of the iPhone outta one case. Single on an iPad. Oh well. Keep em longer too I suppose).
Good to see another avid iOS user. I love both and have since the original 4GB, non subsidized $500 2G iPhone and the Xoom/S1 ...and to date I'm undecided. Don't play with the new Amdroids. They're very nice as well. It's too dangerous now with AT&T/Verizon, even Best Buy, etc. just pick what you want. The color. The capacity. No money down and NEXT fools ya. Before you know it, you've got iPads for everyone in the family. A pair of Nexus 7s you're trying to figure out what to do with, iPhones and Notes... Just 'try' the M9, or the G3/(4 coming?) what the heck, can't hurt. Before you know it you've got a dozen devices all accessing your data, exponentially increases bandwidth used on wifi and LTE for updates and the ilk. And a $700 'phone' bill. Lol. Too cool.
Does t matter which way you go, iPhone 5s/6/6+ or S5/Note4/G3/M8 or 9, Note 4 or this bad boy. They're ALL 'computers' in our pocket. Across the board faster and more energy efficient than computers we used last decade. The storage. The connectivity. The processing and RAM, controllers (micro); accelerometer, barometer, proximity and Bluetooth 4.1, wireless AC and 2x2 antenna arrangement ...without... An antenna ( those of us in our forties, probably mid to late thirties remember those, right? ...other than the sweet 'bands' on my 6+;) course hidden by earlier do dissed Apple's iPhone case. iPad cases. They're sweet. Kinda like their trackpads in comparison to EVERY other OEM. They work. All. The. Time. They NEVER don't. WTH can't Windows get an OEM partner to nail the trackpad? Perhaps that's why they decided on 'touch'? :-)