The HTC M9 and LG G Flex 2, first phones to ship with Snapdragon 810 were running hot and our deep throats in Qualcomm tell is that it was not the chips fault.
Apparently these phones were rushed to market and that chipset was actually running cooler than the Snapdragon 805.
The Snapdragon 820 needs 30 percent less power than the Snapdragon 810, and at the same time, the 810 needs less power than the Snapdragon 805.
Yet people haven’t been complaining about the Snapdragon 805 running too hot. The list of design wins includes Samsung S5 LTE-A Korea, LG G3 Cat 6, Samsung Galaxy Note 4 LTE, Samsung Galaxy Note Edge, Amazon Fire HDX 8.9, Motorola Droid Turbo, , Inforce IFC6540, Samsung Galaxy Note 4 Duos and Xiaomi Mi Note.
The Motorola Nexus 6 was a successful phone for Google that didn’t had any thermal issues, at least nothing major. But it appears that the tech press blow everything out of proportion.
The Snapdragon 810 found its place in dozen of phones including many from LG, Samsung, Motorola, ZTE, Xiaomi and HTC but only the first devices had some issues with the thermal throttling.
It looks like the first to market partners didn’t invest necessary time to thermal design, and used SoC throttling and crippled the SoC performance. The "overheating" rumor originated in South Korea, the land of the Samsung and we could see why would Samsung want Snapdragon 810 to fail. Samsung had its own Exynos 7420 that was working better than anyone expected and the company wanted to sell its own, in house chip.
This is probably where the overheating rumour originated, and we have heard the same whispers from Korea about the Snapdragon 820. We saw the SoC the other week and the prototype phones and tablets were fine.