The A8X has three cores clocked at 1.5 GHz, a more powerful GPU compared to the A8 and it contains 3 billion transistors.[8] With an extra 100 MHz and an additional core, the A8X performs around 13% better on single threaded and 55% better on multithreaded operations than the A8 inside the iPhone 6 and iPhone 6 Plus.
Further comparison to the A8 shows that the A8X uses a metal heat spreader, which the A8 does not, and it doesn’t use the package on package configuration with included RAM which the A8 does. This is similar to how the older "X" variants, the A5X and A6X, were designed.[9] Instead the A8X in the iPad Air 2 uses an external 2 GB RAM module