Can I Run Llama 3.1 405B Instruct on a Apple M5 Ultra (256GB)?
Runs at Q4_K_M — good quality with reasonable headroom.
1 quant fit your 256GB
| Quant | Min VRAM | Recommended | File size | Headroom |
|---|---|---|---|---|
| Q4_K_MBEST | 246.5 GB | 248.0 GB | 245.5 GB | +9.5 GB |
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FAQ
Can the Apple M5 Ultra (256GB) run Llama 3.1 405B Instruct?
Yes. The Apple M5 Ultra (256GB)'s 256GB of unified memory is enough to run Llama 3.1 405B Instruct at Q4_K_M quantization (246.5GB required).
What's the best quantization to use?
Q4_K_M is the highest-precision quantization that fits in your 256GB. It uses about 246.5GB of memory and 248.0GB 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.