Apple A12X
The Apple A12X Bionic is a 64-bit system on a chip (SoC) designed by Apple Inc. It first appeared in the iPad Pro (3rd generation), announced on October 30, 2018. The A12X is an 8-core variant of the A12 (four big cores, four small cores) and Apple states that it has 35 percent faster single-core CPU performance and 90 percent faster overall CPU performance than its predecessor, the Apple A10X. The A12X's design is also used in the Apple A12Zand the Apple M1.

Design 
The A12X features an Apple-designed 64-bit ARMv8.3-A octa-core CPU, with four high-performance cores called Vortex and four energy-efficient cores called Tempest. The Vortex cores are a 7-wide decode out-of-order superscalar design, while the Tempest cores are a 3-wide decode out-of-order superscalar design. The Tempest cores are based on Apple's Swift cores from the Apple A6, and are similar in performance to ARM Cortex-A73 CPU cores. It is Apple's first SoC with an octa core CPU. 

The A12X integrates an Apple-designed hepta core graphics processing unit (GPU) with twice the graphics performance of the A10X. Embedded in the A12X is the M12 motion coprocessor. The A12X includes dedicated neural network hardware that Apple calls a "Next-generation Neural Engine". This neural network hardware, which is the same as found in the A12, can perform up to 5 trillion operations per second.

The A12X is manufactured by TSMC using a 7 nm FinFET process, and it contains 10 billion transistors vs. the 6.9 billion on the A12. The A12X is paired with 4 GB of LPDDR4X memory in the third-generation 12.9" iPad Pro and the 11" iPad Pro or 6 GB in the 1TB storage configurations.

The support of Codecs by decoding and encoding is extended to HEVC 264, 265 (8/10bit), VP 8, VP9 and JPEG. AVC and VC1 are available for decoding. AV1 is not supported by hardware.

Products that include the Apple A12X 
 iPad Pro 11-inch (1st generation)
 iPad Pro 12.9-inch (3rd generation)

See also 
 Apple silicon, the range of ARM-based processors designed by Apple.
 Apple A12
 Apple A12Z

References 

A12X
ARM architecture
Computer-related introductions in 2018
64-bit microprocessors