Apple Apple Watch Series 8 / Ultra's S8 chip is equipped with the same CPU as S6 / S7: TSMC 7nm process

The S8 chip in the Apple Watch Series 8, Apple Watch Ultra and Apple Watch SE 2 has the same CPU as the S6 and S7 chips, according to the identifier code.

The CPU in the Apple S8 SiP has the same T8301 identifier as the CPU in the S6 and S7 chips that debuted in the Apple Watch Series 6 and Apple Watch Series 7. This explains why Apple has only compared the S Series chip to the S5 chip or earlier in recent years.

It also means that the Apple Watch Series 6, Apple Watch Series 7, Apple Watch Series 8, Apple Watch Ultra, and Apple Watch SE 2 all have the exact same CPU. Note that Apple may still be iterating on other parts of the SiP to accommodate new components, such as the new accelerometer and gyroscope support for the Apple Watch Series 8.

The Apple S6, S7 and S8 chips all come with 32GB of storage and a dual-core CPU. when Apple debuted the S6 in the Apple Watch Series 6, it was the last time it made a performance statement about its latest smartwatch line, "the chip makes apps launch 20 percent faster.

The Apple S6, S7 and S8 are based on the A13 bionic chip found in the iPhone 11 series and manufactured using TSMC's 7nm process. Apple began the transition to TSMC's 5nm process with the A14 Bionic chip, and the A16 Bionic in the iPhone 14 Pro was the first Apple chip to be built using the 4nm process.

One explanation for Apple not advancing CPU technology in its S-series chips is that the advancements from using the A14 chip and cores in TSMC's 5nm or 4nm process may be primarily performance improvements, but that's no longer important for the Apple Watch. Waiting for TSMC to produce the 3nm process, which will enter volume production by the end of this year, may yield more meaningful efficiency gains -- which is more important for the Apple Watch because it helps extend battery life.