Written by Jakub Rusinowski · Last updated August 15, 2026
Yes — comfortably
Yes, comfortably — GPT-oss 120B at Q5_K_M needs about 86.5 GB of the 144 GB usable on Mac Studio (M2 Ultra, 192 GB), leaving ~57.5 GB spare and running at ~5.1 tok/s (estimated), with room for about 65,536 tokens of context.
Confidence: high · Recommended quantization: Q5_K_M · Estimated speed: ~5.1 tok/s
| Usable memory for models | 144 GB |
| Memory bandwidth | 800 GB/s |
| Form factor | Desktop |
| Operating system | macOS |
| Memory upgradeable | No — soldered |
| Quant | Memory needed | Fits 144 GB? | Max context | Est. speed | Download |
|---|---|---|---|---|---|
| F16 | 241.4 GB | ✗ No | — | — | 240 GB |
| Q8_0 | 128.9 GB | ✓ Yes | 64K | ~3.4 tok/s | 127.5 GB |
| Q6_K | 99.8 GB | ✓ Yes | 64K | ~4.4 tok/s | 98.4 GB |
| Q5_K_M | 86.5 GB | ✓ Yes | 64K | ~5.1 tok/s | 85.1 GB |
| Q4_K_M | 73.9 GB | ✓ Yes | 64K | ~5.9 tok/s | 72.5 GB |
| Q3_K_M | 52.6 GB | ✓ Yes | 64K | ~8.3 tok/s | 51.2 GB |
| Q2_K | 40.9 GB | ✓ Yes | 64K | ~10.7 tok/s | 39.4 GB |
| Variant | Needs at Q4_K_M | Fits? | Est. speed |
|---|---|---|---|
| GPT-oss 120B | 73.9 GB | ✓ Fits | ~5.9 tok/s |
| GPT-OSS 20B | 13.3 GB | ✓ Fits | ~32.3 tok/s |
Ollama or LM Studio (Metal) — MLX for the fastest Apple-native throughput
Yes, comfortably — GPT-oss 120B at Q5_K_M needs about 86.5 GB of the 144 GB usable on Mac Studio (M2 Ultra, 192 GB), leaving ~57.5 GB spare and running at ~5.1 tok/s (estimated), with room for about 65,536 tokens of context.
Q5_K_M — it needs about 86.5 GB of the 144 GB available, downloads as roughly 85.1 GB, and runs at an estimated 5.1 tokens/sec with up to 64K of context.
Nothing binding — the model fits with headroom and generates at a usable speed on this hardware.
Ollama or LM Studio (Metal) — MLX for the fastest Apple-native throughput