Anandtech has an excellent article on the new Apple A8X processor that powers the iPad Air 2. This is an interesting processor for Apple, but perhaps more interesting is its use, and the reasoning for it. Like the A5X and A6X before it (there was no A7X) it is an upgrade/enhancement from the A8 it is based on. In the A5X the CPU was moved from a single core to a dual core and the GPU was increased from a dual core PowerVR SGX543MP2 to a quad-core PowerVR SGX543MP4. The A6X kept the same dual core CPU design as the A6 but went from a tri-core SGX543MP3 to a quad core SGX554MP4. Clock speeds were increased in the A5X and A6X over the A5 and A6 respectively.
The A8X continues on this track. The A8X adds a third CPU core, and doubles the GX6450 GPU cores to 8. This is interesting as Imagination Technologies (whom the GPUs are licensed from) doesn’t officially support or provide an octa-core GPU. Apple;s license with Imagination clearly allows customization though. This is similar to the ARM Architecture license that they have. They are not restricted to off the shelf ARM, or Imagination cores, they have free reign to design/customize the CPU and GPU cores. This type of licensing is more expensive, but it allows much greater flexibility.
This brings us to the why. The A8X is the processor the the newly released iPad Air 2, the previous iPad air ran an A7, which wasn’t a particularly bad processor. The iPad Air 2 has basically the same spec’s as the previous model, importantly the screen resolution is the same and no significantly processor intense features were added.
When Apple moved from the iPad 2 to the iPad (third gen) they doubled the pixel density, so it made sense for the A5X to have additional CPU and GPU cores to handle the significantly increased amount of processing for that screen. Moving from the A7 to the A8 in the iPad Air 2 would make clear sense from a battery life point of view as well, the new Air has a much smaller batter so battery life must be enhanced, which is something Apple worked very hard on with the A8. Moving to the A8X, as well as doubling the RAM though doesn’t tell us that Apple was only concerned about battery life (though surely the A8X can turn on/off cores as needed). Apple clearly felt that the iPad needed a significant performance boost as well, and by all reports the Air 2 is stunningly fast.
It does beg the question though? What else may Apple have in store for such a powerful SoC?