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The Snapdragon 810’s Thermal Throttling Examined, Compared to Other SoC’s

April 24, 2015 - Written By Nick Sutrich

For years now Qualcomm has ruled the roost of the mobile System on a Chip (SoC) world, powering billions of phone that have launched since the smartphone wars really started to heat up.  Last year’s releases were some of the best ever, showing not only incredible performance and an amazing featureset but also some absolutely killer battery life in the form of the Snapdragon 801 and 805.  In the move to 64-bit Qualcomm seems to have lost a bit of its magic though, going for a reference ARM design over the custom designs they’ve been making in-house for years.  We could speculate forever as to why this was done but at the end of the day the Samsung Exynos 7420 features the exact same Cortex A53 and A57 CPU cores at its heart, yet runs faster and cooler than the Snapdragon 810.

For a while we had thought that the thermal issues were put to rest alongside rumors of phones not using the 810, however after Samsung officially dropped the 810 in favor of its Exynos 7420 and it looks like a number of other companies are making similar moves, the question is beckoning again.  We’ve reviewed both the LG G Flex 2 and the HTC One M9, both phones that launched in the past couple of weeks and are powered by the Snapdragon 810.  In the reviews we noted the sluggish nature of the phones, and while HTC seems to have done a better job of mitigating performance issues with the 810 it’s still more obvious than it should be.  In a technical analysis Arstechnica broke down the Snapdragon 810’s performance and assembled the data from Geekbench in some nice, neat little graphs.  They compared the Snapdragon 810 with the 805 and even the 801, as well as the Samsung Exynos 7420 to show the difference in the engineering that went into these processors.

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The results are stunning to say the least.  At its fastest the 810 and Exynos 7420 go neck and neck in performance tests, no surprise again given that they run the exact same CPU cores, however the 810 has to slow down well before the Exynos, creating performance hurdles that simply cannot be jumped over via software.  Looking at the Snapdragon 810 we see from a stress test that the CPU actually only reaches its peak speed of 2.0GHz for a brief moment around the 50-second mark.  Only 90-seconds into the test the CPU starts to throttle hard, dropping as low as 1.0GHz and only jumping up to 1.4GHz as it is able to given the thermal output.  At only 180 seconds we see it drop to the minimum speed of 850MHz, a speed that’s drastically lower than any newer processor out there and a trend that continues for the rest of the test.  After just 8 minutes the Snapdragon 810 isn’t even able to jump above a paltry 950MHz, a speed that’s likely to destroy any performance a user has been enjoying out of that game or movie they’re watching.

Meanwhile looking at the Samsung Exynos 7420 during the exact same test we see it reaching its peak speed of 2.1GHz immediately, only significantly throttling after 120-seconds down to 1.7GHz.  It isn’t until 5.5 minutes in that we see it even drop lower to 1.4GHz and even then for the rest of the 15-minute test it jumps back up to 2.1GHz fairly often, with dips as low as 1.2GHz when needed.  This shows significantly better thermal management and an obvious better chip design this time around, which shows that Samsung indeed has made the right decision in going with its own processors over Qualcomm’s this time around.  Even comparing the 810 to the 805 and 801 is a staggering difference, and the performance of both those chips eclipses the 810 after just a few minutes thanks to the thermal issues we’re seeing.  Check out the graphs below for all the data and don’t be surprised if we see more ramifications in the mobile industry because of this report.