Apple Watch S8 chip is equipped with the same CPU as S6/S7: TSMC process

According to the identifier codes, 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.

The CPU in Apple's S8 SiP carries 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 S-series chips to S5 chips or earlier in recent years.

This also means that the Apple Watch Series 6, Apple Watch Series 7, Apple Watch Series 8, Apple Watch Ultra, and Apple Watch SE 2 are all equipped with the exact same CPU. It is worth noting that Apple may still be iterating on other parts of the SiP to accommodate new components, such as the Apple Watch Series 8 supporting new accelerometers and gyroscopes.

Apple's S6, S7, and S8 chips all come with 32GB of storage and dual-core CPUs. When Apple first introduced the S6 in the Apple Watch Series 6, it was the last time it made a performance claim for its latest smartwatch line: "The chip enables apps to launch 20 percent faster."

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

One explanation for why Apple hasn’t advanced CPU technology in its S-series chips is that the advances made with the A14 chip and cores made in TSMC’s 5nm or 4nm processes are likely to be mostly performance improvements, but that’s no longer important for the Apple Watch. Waiting for TSMC’s mass-produced 3nm process, which is set to enter volume production by the end of this year, could yield more meaningful efficiency gains — which are more important for the Apple Watch because it helps extend battery life.