Can I Run / Qwen 3.5 397B A17B / on Apple M3 Ultra (512GB)

Can I Run Qwen 3.5 397B A17B on a Apple M3 Ultra (512GB)?

Yes

Runs at Q8_0 — near-lossless quality.

Model size
397B
GPU memory
512GB
Smallest quant
Q4_K_M
Best fit
Q8_0

4 quantizations fit your 512GB

QuantMin VRAMRecommendedFile sizeHeadroom
Q8_0BEST422.8 GB424.3 GB421.8 GB+89.2 GB
Q6_K328.0 GB329.5 GB327.0 GB+184.0 GB
Q5_K_M282.9 GB284.4 GB281.9 GB+229.1 GB
Q4_K_M241.7 GB243.2 GB240.7 GB+270.3 GB

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Full model details
Qwen 3.5 397B A17B

All quant variants, benchmark scores, and use-case tags.

Best models for this GPU
Apple M3 Ultra (512GB)

Top-ranked open-source models that fit in 512GB.

FAQ

Can the Apple M3 Ultra (512GB) run Qwen 3.5 397B A17B?

Yes. The Apple M3 Ultra (512GB)'s 512GB of unified memory is enough to run Qwen 3.5 397B A17B at Q8_0 quantization (422.8GB required).

What's the best quantization to use?

Q8_0 is the highest-precision quantization that fits in your 512GB. It uses about 422.8GB of memory and 424.3GB recommended for comfortable inference.

What if I need more headroom for context length?

KV cache memory grows with context length. The numbers above assume a baseline 2K-4K context. For long-context use (32K+), add another 2-6GB depending on the model architecture.