A thorough dissection of Apple’s new A9X processor, at the heart of the 12.9-inch iPad Pro, has revealed that the silicon features a custom 12-cluster GPU, effectively doubling the graphics performance of the base A9 processor currently powering the iPhone 6s.
As originally reported to The Motley Fool, a pair of silicon experts at Chipworks recently took an X-ray of the A9X processor, ultimately discovering two CPU cores alongside 12 GPU clusters that are paired in twos.
The GPU design is perhaps most notable because Apple’s GPU partner, Imagination Technologies, currently offers its Series7XT graphics in only cluster sizes of 2, 4, 6, 8, and 16. That means, in other words, that the GPU found in the A9X has to be a semi-custom piece built collaboratively with Apple.
Also allowing Apple to double the number of clusters from 6 to 12 is the A9X’s size, which is 40% larger, and thus supports an ample amount of extra space space over the iPhone 6s’s A9 chip.
Additionally, the processor that was examined by Chipworks was found to have been built by Taiwan Semi-conductor Corp (TSMC). Currently unknown, however, is if TSMC is handling the manufacturing of all A9X processors, which would make sense seeing as how Apple decided to split production of the A9 chip between TSMC and Samsung.
Historically speaking, Apple prefers to keep the detailed technical specifications of its custom A-series chips on the hush, while instead focusing on real-world performance that could be achieved by the processors. For instance, Apple has touted that the A9X chip is “1.5 times faster than a comparable desktop processor, while graphics performance is twice as fast as the A8X CPU in the 2014 iPad Air 2.”
Similarly, Apple has gone on record saying that the iPad Pro is faster than “80 percent of the portable PCs shipped in the last 12 months, while still boasting 10 hours of battery life on a single charge.”
Interestingly enough, the Chipworks assessment of the A9X found that the silicon is missing the 8 megabytes of on-die memory found on the A9 chip in the iPhone 6s. Ashraf Eassa of The Motley Fool had speculated that the A9X is equipped with a substantially larger memory interface, allowing data to be sent to memory about two times faster than the A9. This is possible, he claimed, in part because of the larger size capacity of the A9X.
The A9X chip also features 4 GB of RAM, a number which doubles the amount of memory found in the iPad Air 2 and iPhone 6s. Performance is further aided by a new, on-chip storage mechanism that improves both read and write speeds.