What is the best local LLM for a Mac Studio M3 Ultra?

With its huge unified memory, the M3 Ultra runs Llama 3.3 70B at Q8 (near-full quality) and 100B+ MoE models like gpt-oss 120B locally at ~25-30 tokens/sec. For OpenClaw you can even keep several models resident at once for multi-agent setups.

How much unified memory does the M3 Ultra have?

It depends on when you bought it. The M3 Ultra Mac Studio originally configured up to 512 GB of unified memory at roughly 800 GB/s. Apple removed the 512 GB option in early March 2026 and the 256 GB option on May 5, 2026, so as of August 2026 the only configuration Apple sells new is 96 GB, starting around $5,299. 96 GB still holds a 70B model at Q8 and a 120B-class MoE at Q4, but 256 GB and 512 GB machines are now used-market only, and they price on scarcity rather than depreciation.

Is the M3 Ultra fast for local LLMs?

For its class, yes. The ~800 GB/s bandwidth delivers ~25-30 tokens/sec on 70B-class models — much faster than an M4 Pro and enough for comfortable interactive use, though still below datacenter GPUs on raw throughput.

M3 Ultra vs M4 Max for local AI?

The M3 Ultra wins on bandwidth (~800 vs ~410 GB/s), so it runs big models faster. The memory-ceiling gap has narrowed on new hardware: as of August 2026 Apple sells the M3 Ultra Mac Studio only in 96 GB and the M4 Max Mac Studio only up to 64 GB, so the choice is 96 GB at ~800 GB/s from about $5,299 versus 64 GB at 546 GB/s from about $2,499. The M4 Max is much cheaper and plenty for 70B at Q4; choose the Ultra when you need 70B at Q8, a 120B-class MoE, or multiple resident models.

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Hardware July 6, 2026

Best Local LLM for Mac Studio M3 Ultra (2026): 96GB New, 512GB Used

The Mac Studio M3 Ultra runs unified memory at ~800 GB/s and puts models on your desk that no single consumer GPU can touch. One important update since this page was written: Apple removed the 512GB configuration in March 2026 and the 256GB configuration on May 5, 2026. As of August 2026 the M3 Ultra Mac Studio ships in exactly one memory tier, 96GB, from about $5,299. The big-memory configs are a used-market product now.

Picking hardware for an OpenClaw host?

Use the local model calculator first, then see our AI training options if you want help matching your workload to the right rig.

Short answer: the M3 Ultra is still the top consumer local-LLM machine for sheer model size, and it now comes in one size. It runs Llama 3.3 70B at Q8, 100B+ MoE models (gpt-oss 120B, Mistral Small MoE), and very long context — all locally at ~25-30 tok/sec. The ~800 GB/s bandwidth makes it noticeably faster than an M4 Max for big models.

Availability update, August 2026. Apple pulled the 512 GB M3 Ultra configuration in early March 2026 and the 256 GB configuration on May 5, 2026, in the middle of the global DRAM shortage. The only M3 Ultra Mac Studio you can order new is 96 GB, from about $5,299 — up from a $3,999 starting price at launch. Everything below still applies at 96 GB; where a model needs more than that, you are shopping used or refurbished, and those machines price on scarcity rather than depreciation. Details: best models for the biggest Mac Studio.

The Memory Math

96 GB of unified memory is enough for 70B at Q8, a 120B-class MoE at Q4, and one large model plus a small router model resident at the same time. That covers most single-operator OpenClaw setups. What 96 GB does not do is the thing the 512 GB machine was famous for — holding a 400B-class model at native precision, or keeping four large models loaded for a multi-agent fleet. If that is your requirement, the new-hardware answer no longer exists at Apple and you are looking at the used market or a DGX Spark cluster.

What Actually Fits (Model Picks)

Model	Quant	Memory	Speed	Notes
Llama 3.3 70B	Q8_0	~75 GB	~25 tok/s	70B at near-full quality
gpt-oss 120B (MoE)	Q4/Q5	~70-90 GB	~28 tok/s	Flagship MoE, runs locally
Qwen 3.6 27B	Q8_0 + huge ctx	~30 GB	~40 tok/s	27B with massive context
Multiple models resident	mixed	fits easily	—	Run several at once for agents

What You Can’t Run

Beating a datacenter GPU on raw throughput — Apple bandwidth is high for a desktop but below an H100-class card; expect ~25-30 tok/s, not hundreds.
Training large models — this is an inference machine, not a training rig.
Cheap — the value case is “runs models a $30k GPU box would,” not low price.

🎮 THE BIG-MEMORY APPLE SILICON PICK

The M3 Ultra Mac Studio now ships in one memory tier, 96 GB (from about $5,299 as of August 2026) — still the fastest big-memory machine you can put on a desk, and no longer the 512 GB flex it was at launch. A 48 GB+ Mac is the entry to 70B; the Mac mini M4 is the budget always-on host for smaller models, starting at $799 for 16 GB now that Apple has dropped the 256 GB storage SKU.

48GB+Premium Mac 48 GB+ ↗ MINIMac mini M4 ↗

OpenClaw Setup

Point OpenClaw at your local model through Ollama:

# pull and run your pick, then set it as the OpenClaw default
ollama pull llama3.3:70b
openclaw config set agents.defaults.models.chat "ollama/llama3.3:70b"

For agent reliability, prefer a model with clean tool-call output (gpt-oss 20B where it fits) and cap context to what your memory holds. See the tool-calling reliability guide.