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Setting things up for what is certainly to be an exciting next few months in the world of CPUs and SoCs, Apple this morning has announced their next-generation M-series chip, the M4. Introduced just over six months after the M3 and the associated 2023 Apple MacBook family, the M4 is going to start its life on a very different track, launching alongside Apple’s newest iPad Pro tablets. With their newest chip, Apple is promising class-leading performance and power efficiency once again, with a particular focus on machine learning/AI performance.
The launch of the M4 comes as Apple’s compute product lines have become a bit bifurcated. On the Mac side of matters, all of the current-generation MacBooks are based on the M3 family of chips. On the other hand, the M3 never came to the iPad family – and seemingly never will. Instead, the most recent iPad Pro, launched in 2022, was an M2-based device, and the newly-launched iPad Air for the mid-range market is also using the M2. As a result, the M3 and M4 exist in their own little worlds, at least for the moment.
Given the rapid turn-around between the M3 and M4, we’ve not come out of Apple’s latest announcement expecting a ton of changes from one generation to the next. And indeed, details on the new M4 chip are somewhat limited out of the gate, especially as Apple publishes fewer details on the hardware in its iPads in general. Coupled with that is a focus on comparing like-for-like hardware – in this case, M4 iPads to M2 iPads – so information is thinner than I’d like to have. None the less, here’s the AnandTech rundown on what’s new with Apple’s latest M-series SoC.
At a high level, the M4 features some kind of new CPU complex (more on that in a second), along with a GPU that seems to be largely lifted from the M3 – which itself was a new GPU architecture. Of particular focus by Apple is the neural engine (NPU), which is still a 16-core design, but now offers 38 TOPS of performance. And memory bandwidth has been increased by 20% as well, helping to keep the more powerful chip fed.
One of the few things we can infer with a high degree of certainty is the manufacturing process being used here. Apple’s description of a “second generation 3nm process” lines up perfectly in timing with TSMC’s second-generation 3nm process, N3E. The enhanced version of their 3nm process node is a bit of a sidegrade to the N3B process used by the M3 series of chips; N3E is not quite as dense as N3B, but according to TSMC it offers slightly better performance and power characteristics. The difference is close enough that architecture plays a much bigger role, but in the race for energy efficiency, Apple will take any edge they can get.
Apple’s position as TSMC’s launch-partner for new process nodes has been well-established over the years, and Apple appears to be the first company out the door launching chips on the N3E process. They will not be the last, however, as virtually all of TSMC’s high-performance customers are expected to adopt N3E over the next year. So Apple’s immediate chip manufacturing advantage, as usual, will only be temporary.
Apple’s early-leader status likely also plays into why we’re seeing the M4 now for iPads – a relatively low volume device at Apple – and not the MacBook lineup. At some point, TSMC’s N3E production capacity with catch up, and then-some. I won’t hazard a guess as to what Apple has planned for that lineup at that point, as I can’t really see Apple discontinuing M3 chips so quickly, but it also leaves them in an awkward spot having to sell M3 Macs when the M4 exists.
No die sizes have been quoted for the new chip (or die shots posted), but at 28 billion transistors in total, it’s only a marginally larger transistor count than the M3, indicating that Apple hasn’t thrown an excessive amount of new hardware into the chip. (ed: does anyone remember when 3B transistors was a big deal?)
Starting on the CPU side of things, we’re facing something of an enigma with Apple’s M4 CPU core design. The combination of Apple’s tight-lipped nature and lack of performance comparisons to the M3 means that we haven’t been provided much information on how the CPU designs compare. So if M4 represents a watershed moment for Apple’s CPU designs – a new Monsoon/A11 – or a minor update akin to the Everest CPU cores in A17, remains to be seen. Certainly we hope for the latter, but absent further details, we’ll work with what we do know.
Apple’s brief keynote presentation on the SoC noted that both the performance and efficiency cores implement improved branch predication, and in the case of performance cores, a wider decode and execution engine. However these are the same broad claims that Apple made for the M3, so this is not on its own indicative of a new CPU architecture.
What is unique to Apple’s M4 CPU claims however are “next-generation ML accelerators” for both CPU core types. This goes hand-in-hand with Apple’s broader focus on ML/AI performance in the M4, though the company isn’t detailing on just what these accelerators entail. With the NPU to do all of the heavy lifting, the purpose of AI enhancements on the CPU cores is less about total throughput/performance and more about processing light inference workloads mixed inside more general-purpose workloads without having to spend the time and resources firing up the dedicated NPU.
