Yesterday we received our Galaxy S6 and S6 edge review units. We’re still working on the final review but I wanted to share some early results from both devices. For those that are unfamiliar with these two phones, the Galaxy S6 range represents the result of Samsung’s “Project Zero”. In fact, the phones seem to have the internal name of Zero, which can be seen in terminal, and the build properties of both devices. For Samsung, these phones represent their attempt at completely rethinking how Samsung makes phones. There is a strong emphasis on a new unibody design, which has no visible gaps or screws. Rather than the plastic that previous Samsung phones have been known for, the new design is composed of metal and glass. Samsung’s design team has been given unprecedented control throughout the process of making this phone and the result of this is a Galaxy phone that looks unlike anything else they’ve ever released.

Even if design is important, it isn’t enough to make the phone. Samsung has also outfitted the Galaxy S6 and S6 edge with their latest technologies, from a new AMOLED display to a new camera module. The specs for both phones can be seen below.

Both the Galaxy S6 and S6 edge have Samsung System LSI’s newest SoC, the Exynos 7420, which has a cluster of four Cortex A57s clocked at 2.1 GHz, and four Cortex A53s clocked at 1.5 GHz. Compared to the Exynos 5433 of the Galaxy Note 4, this brings a new 14nm LPE (low power early) process, an upgrade to LPDDR4 memory, and a Mali T760 GPU with two additional shader cores. Outside of the SoC, the new display is advertised to bring a higher 600-nit brightness and a higher 1440p resolution. The front and rear cameras are both different from the Galaxy S5 as well, although the rear camera sensor may be shared between the two as the camera sensors are of similar spec. For this preview, we’ll focus on the system performance and display of these new devices, but as one can see from the specification table there is far more to look at for the full review.

System Performance

For our system performance benchmarks we’ll start with our browser tests which can give a rough proxy for overall CPU performance.

The Exynos 7420 is about on par with the Snapdragon 810 in these benchmarks. Strangely enough both tend to do worse than the Huawei Honor 6 in these tests, which clearly can't be correct. As we've previously discussed, the stock browser will often give far better results due to OEM and SoC vendor optimizations. As a part of our updates to the benchmark suite for 2015, we'll take a look at Basemark OS II 2.0, which should give a better picture of CPU performance in addition to overall device performance.

The browser benchmarks seem to hide some pretty enormous variability as the Galaxy S 6 edge (which is comparable to the Galaxy S 6) sets a new record among Android devices. The only challenger is the iPad Air 2, which uses the A8X SoC with three Enhanced Cyclone cores and the semi-custom GXA6850 GPU.

This system test contains a floating point and integer test, in addition XML parsing, which means that this test mostly stresses CPU and RAM. Interestingly enough, the Exynos 7420 pulls far ahead of both the Exynos 5433 and Snapdragon 810 in this test, and approaches the A8X. The difference between the 5433 and 7420 is likely a combination of the higher clocks on both the A57 and A53 clusters for the 7420 (1.9/1.3 on the 5433, 2.1/1.5 on the 7420), in addition to the ability to stay at a high 'overdrive' clock due to reduced leakage from the 14LPE process. The One M9 likely falls a bit short here due to HTC's governor settings restricting the use of all 8 cores simultaneously.

While one might guess that the memory test of 'Basemark OS II 2.0 - Memory' is of RAM, this is actually a test of the internal storage. Once again we see the S6 edge come close to leading the pack due to the use of the new UFS (Universal Flash Storage) standard. Casual examination reveals that the S6 edge has a queue depth of 16, and that it identifies itself with the rather cryptic model name of KLUBG4G1BD-E0B1.

For the web test, it uses the built-in WebView rendering engine rather than Chrome and paints a distinctly different picture, especially because these tests are focused on HTML5 and CSS rather than JavaScript. Here we can see that the iPhone 6 and iPad Air 2 continue to hold their lead, but the Galaxy S6 is pretty much the king of the hill when it comes to Android devices.

GPU Performance

As previously discussed, on the GPU Samsung has added two additional shader cores to the Mali T760 for additional performance in addition to a clock speed bump from 700 to 772 MHz maximum. To evaluate the effects of this we look at GFXBench which is generally accepted as a pure GPU benchmark.

From the results the Mali T760MP8 GPU of the Exynos 7420 performs admirably in comparison to the Adreno 430 of the Snapdragon 810. We see a 10% lead over the Adreno 430 in Manhattan, growing to 20% in T-Rex. Qualcomm hinted that the Adreno 430 is more strongly improved in ALU performance over the Adreno 420, which would explain why the gap isn't as significant this generation. A 700 MHz clock on the Adreno 430 would likely equal to T760 in this case, but I suspect the power consumption of such a clock would be untenable. The Galaxy S6 does fall behind on the on-screen benchmarks due to the 1440p display compared to the 1080p display of the One M9, but rendering at a lower resolution would avoid most of these problems in real games.

Display

As previously discussed, the Galaxy S6 line introduces a newer generation of AMOLED displays, which is said to increase maximum luminance to 600 nits. Samsung claims that this was achieved with the use of new materials, which is likely necessary in order to sustain power efficiency improvements. It doesn't seem that AMOLED is uniquely suited to high resolution, but rather that Samsung Display Corp. is managing to dramatically improve how they make AMOLED displays with every year that offset power consumption increases from higher resolution displays. To find out how Samsung did, we use SpectraCal's CalMAN 5 Ultimate, in addition to X-Rite's i1Pro2 Basic to characterize displays as accurately as possible.

From the results Samsung's claims of a 600 nit display are valid in this case, which is a 100% APL white display. It's important to note that achieving this requires the use of auto-brightness, and that manual brightness is limited to a much lower brightness to reduce power usage, here the S6 sees similar maximum brightness as the S5. The S6 edge disappointingly only achieves 272 nits in this mode, a rather low value. I saw color balance shift dramatically in auto-boost mode, which suggests that this operating mode is likely less efficient than manual brightness. As an explanation, we've seen that colors are controlled in AMOLED by voltage while brightness is controlled by PWM (pulse width modulation). As with most recent AMOLED displays, there's no DC bias to the pixels so the contrast really is infinite instead of just a very large number when displaying black.

Galaxy S6

Galaxy S6 edge

Moving on to grayscale, we can see that Samsung has done a pretty good job of controlling the white point and gamma across the saturation sweep, even if green is slightly dominant in both displays. We can also see that there is variation across displays as the S6 edge is closer to neutral while the S6 sample tends a bit warmer.

Galaxy S6

Galaxy S6 Edge

In the saturation sweep, both displays do an incredible job. I really don't have anything else to say here, because there's really no way to improve on the level of calibration Samsung has done on this display. Unless Samsung calibrates every single display in production, which is wildly impractical and effectively impossible to do, this is as good as it gets for a mass-produced device. Improving past this point will also be incredibly difficult to perceive, which means there's no real reason to go any further.

Galaxy S6

Galaxy S6 edge

In the Gretag MacBeth ColorChecker, we can get an idea for overall color accuracy, which paints a picture similar to the saturation test. The only real problem I've noticed with these displays are the viewing angles, which can produce color shifting when the display is tilted. This is a bit of an issue on the edge variant as I can see that the edges of the display appear somewhat green when viewed head on, but otherwise there are no real issues to be seen here. Overall, this is probably the best display anyone will be able to get in a smartphone right now. This level of progress is amazing from Samsung, given just how bad things were with the Galaxy S' AMOLED display, even as recent as the display of the Galaxy S4. With the Galaxy S5 review, I said that I wouldn't be surprised to see AMOLED equal, if not exceed LCD within a year or two, and Samsung has managed to finally hit that mark.

Initial Thoughts

With the Galaxy S6 and S6 edge Samsung claimed that they wanted to completely rethink how they designed and made smartphones. On the surface, it seems that Samsung has delivered on this promise as the Galaxy S6 and S6 edge are unlikely any other Galaxy S phone they have made previously. There is no removable battery, no microSD slot, or even a removable back cover. I would’ve liked to see a microSD slot, but I personally wouldn’t be affected by being limited to 32GB of internal storage. The removable battery issue is a bit concerning for me though, as it’s likely that disassembling this phone to replace the battery will require extensive use of a heat gun to loosen glue that may not adhere properly when reassembled. The materials are now aluminum and glass, which dramatically affect in-hand feel. I definitely like the move to the aluminum and glass design for the improved look and feel of the phone, but the use of the glass back is a bit annoying as the phones have a tendency to slide off pretty much any table. The edge variant of the phone also feels quite sharp in the hand and almost too thin to hold, but this is generally quite subjective.

Outside of design, there is a lot to talk about in the SoC and display. The Exynos 7420 SoC appears to be class-leading in performance, although there is the obvious question of power consumption that still has to be answered. Samsung’s first 14LPE SoC seems promising, although we’ve yet to validate whether big.LITTLE is more efficient than when we last tested it in the Exynos 5433. The GPU is generally quite close to the Adreno 430, with about a 10-20% advantage in performance depending upon the workload, although at the same clock speed it probably wouldn’t have any advantage. The 1440p display can also reduce performance compared to a 1080p display.

Speaking of displays, Samsung has integrated an incredible display into both versions of the Galaxy S6. I’m really blown away at how far AMOLED has come in the past few years, as the Galaxy S6 is one of the best displays we’ve tested for luminance and overall color accuracy. The only real problems I can see are color shifts with viewing angles, and white point tending to be a bit green depending upon the unit we’re looking at. There are some edge-specific issues, namely uneven luminance and odd color shifting towards green hues on white at the edge of the display. Other than this, the display of the Galaxy S6 is relatively perfect with its dark, inky blacks and amazing color.

Obviously an SoC and display aren’t the only issues to discuss in a smartphone, but given the limited time that we’ve had with the device this was all that could be tested. We hope to have our full review for both devices completed in the near future, and to be able to provide the full picture of the Galaxy S6 line at that time. Pre-orders for the US Galaxy S6 variants will begin on March 27^th, and the phone will go on sale on April 10^th throughout the US with 32, 64, and 128 GB SKUs in Black Sapphire, White Pearl, and Gold Platinum. The S6 edge and S6 will be available on AT&T, Sprint, T-Mobile, Verizon, and US Cellular, but on Boost Mobile, Cricket Wireless, and MetroPCS only the S6 will be available.