Can I Run GPT-OSS 120B on a Apple M1 Ultra (128GB)?
Runs comfortably at Q6_K — minimal quality loss.
3 quantizations fit your 128GB
| Quant | Min VRAM | Recommended | File size | Headroom |
|---|---|---|---|---|
| Q6_KBEST | 99.8 GB | 101.3 GB | 98.8 GB | +28.2 GB |
| Q5_K_M | 86.2 GB | 87.7 GB | 85.2 GB | +41.8 GB |
| Q4_K_M | 73.8 GB | 75.3 GB | 72.8 GB | +54.3 GB |
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Top-ranked open-source models that fit in 128GB.
FAQ
Can the Apple M1 Ultra (128GB) run GPT-OSS 120B?
Yes. The Apple M1 Ultra (128GB)'s 128GB of unified memory is enough to run GPT-OSS 120B at Q6_K quantization (99.8GB required).
What's the best quantization to use?
Q6_K is the highest-precision quantization that fits in your 128GB. It uses about 99.8GB of memory and 101.3GB 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.