The snapdragon 810 had been omitted from the 2015 flagships of Samsung as they were causing over heating issues while performing CPU intensive tasks. Samsung didn’t want a defective chip in its phones. it instead opted for the home grown exynos 7420 chipset. Fast forward to the present, Samsung is hell bent on using the Snapdragon 820 in the Galaxy S7 and Note 6.
One of the reason is that the flagship phones might not have been sold in the numbers that Samsung was expecting and the familiar Snapdragon name would provide the necessary boost to sell the phones. We do not have solid information yet Weather the Snapdragon 820 is causing any heat related issues. since Samsung doesn’t like to take any risks for its flagship phones, there has been a severe internal testing regarding the Snapdragon 820 chipset performance under CPU intensive tasks. Samsung is employing different techniques to maintain the temperature of CPU. the first is the software based solution that tweaks the temperature of the CPU to maintain it under the regulated limits and the second is a hardware based solution. Samsung hopes that putting in the thermal radiating pipes will help in maintaining the CPU temperature. similar to the method which is used in laptops to dissipate the heat emitted from the graphic card and processor.
Another reason is that Qualcomm is desperate to get Snapdragon 820 into the flagship phones and Samsung is desperate to get the manufacturing contract of Snapdragon 820. the two Tech companies are helping each other And Snapdragon 820 will make its way into the Galaxy S7 and Note 6. but Samsung doesn’t intend to use the Snapdragon 820 in all the version of its flagship phones. only the United States and Chinese region will get the version with Snapdragon 820 and the international, European and Australian version will have the home grown exynos SOC.
as for my personal opinion I do not care what Samsung does with the internals. If my phone doesn’t get too hot when using heavy applications, then I am fine with the phone and its processor