It looks like Samsung might be in some hot water over its flagship Galaxy S7 smartphone, with some reports stating that after gaming for around 15 minutes, the Galaxy S7 loses 25% of its performance. Overheating could be the issue, which is something that NordicHardware looked into.
Their report states that the SoC performance gets throttled and is forced to reduce its clock speed when the temperature of the chip rises, leaning to rumors that the Exynos 8890 and its 14nm FinFET LPP process might not be perfect. During some 3DMark SlingShot benchmarking, the Galaxy S7 runs at 38C, and over five rounds, the performance begins to fall right off of a cliff.
There are two different Galaxy S7 smartphones in the market, one with the Exynos 8890 processor and another with the Snapdragon 820. If you're purchasing the one with Samsung's own Exynos 8890, you might experience these performance-related problems. Samsung should hopefully come out and address this in the near future.