The iPhone 6S Plus packs a powerful punch besides its 5.5-inch display. The device runs on an Apple A9 system-on-a-chip (SoC) just like its smaller sibling, the 4.7-inch iPhone 6S. But ChipWorks has revealed an interesting tidbit: Not all A9 chips are the same. Instead, two versions exist: one from Samsung (which measures 96mm squared) and…