The Snapdragon 855 Phone Roundup: Searching for the Best Implementationsby Andrei Frumusanu on September 5, 2019 8:30 AM EST
Pitting 8 devices built around same SoC against each other ended up being an interesting exercise for us. In many ways it served as validation of some of the observations we made earlier in the year with the review of the first Snapdragon 855 devices, while also showcasing some rather surprising behaviors, particularly the gaming performance of the pair of gaming-oriented devices we tested today.
CPU Performance Remains A Software Matter
Back in January when we had the pleasure to test Qualcomm’s Snapdragon 855 reference device, we observed that that some benchmarks behaved a little odd and didn’t quite showcase the larger performance boost over the Snapdragon 845 that we had initially expected. These concerns were largely alleviated once we got our hands on the commercial Galaxy S10 with the S855, which showcased notably improved CPU performance thanks to a more reactive scheduler and DVFS configuration.
Over the months, I continued to see difference between the Snapdragon 855 phones, with some phones behaving well, while others showcased some rather conservative performance. Having 8 different phones at hand now I can pretty much say that some vendors delivered their S855 devices with more matured and fine-tuned software stacks than others.
Samsung’s Galaxy S10 remains the phone with the most responsive and fastest software tuning, having the fastest CPU ramp up amongst our tested devices. The OnePlus 7 Pro as well as the ZTE RedMagic 3 closely followed as the snappiest devices.
In terms of AI performance, we have come to the conclusion it’s also mostly a matter of software, this time in drivers. We saw some phones today that lacked the most up-to-date or best performance drivers, so even though again it’s the same chipset for all the phones, we've observed that performance can be different depending on the workloads. Some S855 phones even lacked the proper drivers altogether, and thus we couldn’t even complete the full machine learning inferencing test suite.
What is clear, however, is that none of the devices today were in any way bad performers. All the phones were able to offer excellent device experiences, and Qualcomm still largely maintains its leadership in this performance aspect, only really facing competition within the Android space from Huawei’s Kirin chipsets.
GPU Performance Is About Heat - How To Dissipate it And How Hot It Gets
Meanwhile, when it comes to the GPU performance, the performance of the phones ended up ranging rather widely.
At the very top of the charts we found the OnePlus 7 Pro alongside the OPPO Reno 10x. Both devices don’t exhibit any notable thermal throttling at all on the GPU, and thus are able to squeeze out the most out of the Adreno 640 in the Snapdragon 855. These high levels of performance however don’t come for free; both devices get exceedingly hot, with peak skin temperatures reaching over 50°C. The OPPO even interrupted our testing session with a device overheating warning – something we’ve seen quite a few times on Snapdragon phones over the last 2 years.
The rest of the devices ended up at various points on the performance curve, being heavily influenced by their physical thermal dissipation ability as well as their software thermal throttling configuration. In general, depending on environmental conditions, one can expect anywhere from a 20% to 40% degradation in performance over longer (30+ minutes) playtime sessions – that is to say if the game you’re playing is fully stressing the Adreno 640 GPU.
The most surprising results overall came from the GPU performance of the Xiaomi Black Shark 2 – and unfortunately things didn’t quite end up where we expected them to for the gaming phone. While the phone is advertised as being gaming-focused, it posted the worst sustained performance characteristics of all the Snapdragon 855 phones, barely showcasing much improvement even over last year’s original Black Shark.
We’ve also seen that different phones have different thermal limitations for the CPU and GPU. For example, Sony’s Xperia 1 clearly has a very aggressive CPU throttling mechanism; however it gives the GPU quite a lot of thermal headroom, ending up performing quite well in our set of benchmarks. Samsung’s S10 ended up in the lower half of the pack, performing below average.
Overall the clear winner in terms of representing the best Snapdragon 855 gaming performance goes to the OnePlus 7 Pro, as its hardware design is the best in terms of distributing the SoC heat throughout the whole body of the phone, and thus being able to maintain the highest performance even at a cost of higher skin temperatures.
Today’s test results reinforce a notion that I’ve been trying to spread over the last couple of years, and that is the better your power efficiency is, the better your performance will be. Over the last few generations Qualcomm’s rate of improvement seems to have slowed down, and our data shows that Apple’s SoCs now power the best-performing devices. Among the Android vendors however, Qualcomm has maintained a measurable lead both in terms of performance as well as the user-experience. Qualcomm’s strength here is the software, and although we’ve seen some differences today with the various Snapdragon 855 implementations, hopefully we’ll see more harmony in then next generation of chipsets.