The Mac lineup now requires a spreadsheet

Apple refreshed the MacBook Air with M4 and the Mac Studio with a choice of M4 Max or M3 Ultra. Read that last part again.

The Mac Studio's top configuration uses a previous-generation chip family because M4 Ultra does not exist — the M4 Max apparently lacks the interconnect that made the Ultra fusion possible, so the highest-end desktop part is an M3 generation die. This is defensible as engineering and indefensible as naming.

what the hardware actually is#

MacBook Air M4. Better base memory, a 12MP center-stage camera, support for two external displays with the lid open, and a starting price that came down. For a developer machine this is the sweet spot it has been for two years: silent, long battery life, and fast enough that the fanless design is not a compromise for anything short of sustained compilation.

Mac Studio M3 Ultra. Up to 512 GB of unified memory. That number is the story. There is currently no other desktop workstation where you can put half a terabyte of memory directly addressable by a capable GPU at reasonable bandwidth.

For local model work this is a genuinely unique product. A 512 GB configuration holds a frontier-scale open-weights model in memory at reasonable quantization, running on a machine that sits on a desk and draws a few hundred watts. There is no comparable option. The nearest equivalents are multi-GPU servers that cost more, sound like a jet, and require a dedicated circuit.

Mac Studio M4 Max. Faster single-thread, fewer memory options, better for most people who are not loading enormous models.

the memory bandwidth caveat#

Capacity is not throughput. The Ultra's memory bandwidth is high by desktop standards and low compared to an H100's HBM. If you load a very large model into 512 GB, you will be able to run it, and it will generate tokens at a rate that is useful for batch work and frustrating for interactive chat.

This is the right trade for a lot of workloads — running evals overnight, processing a corpus, fine-tuning something small — and the wrong trade if you expected an interactive frontier model on your desk.

the naming problem, seriously#

Apple now ships M1 through M4, each in base / Pro / Max / Ultra variants, released on staggered schedules, sold simultaneously in different products. The current lineup contains M2, M3 and M4 generation silicon in actively-sold Macs.

The consequence for developers is real: "requires Apple Silicon" is no longer a useful compatibility statement, and neither is "M-series." Feature availability varies by generation — hardware ray tracing arrived in M3, the improved neural engine in M4 — so if you are targeting these capabilities you need to check the generation, not the family.

sysctl -n machdep.cpu.brand_string will tell you what you are on. You are going to need it.