Yes — GPT-oss 120B (117B-A5.1B) runs at 97 tok/s on M5 Ultra with 96 GB RAM using MXFP4 quantization via MLX. OpenAI's 120B open-source model — high quality, needs 128 GB Mac.
Want to run GPT-oss 120B faster — or step up to bigger models? Find your Mac →The LLMCheck index estimates GPT-oss 120B on M5 Ultra using our published methodology: Q4_K_M quantization, memory-bandwidth scaling, and cross-referenced third-party benchmarks where available. Figures are transparent estimates — own this config? Submit a real benchmark →
| Metric | Value |
|---|---|
| Tokens per second | 97 tok/s |
| Time to first token | — |
| Quantization | MXFP4 |
| Minimum RAM | 96 GB |
| Recommended engine | MLX |
| Parameters | 117B-A5.1B |
| Benchmark date | 2026-08 |
MXFP4 117B-A5.1B MLX M5 Ultra
The recommended engine for GPT-oss 120B on M5 Ultra is MLX. Install with pip and pull the model:
Alternatively, you can use Ollama for a simpler setup:
To run GPT-oss 120B on M5 Ultra you need:
GPT-oss 120B needs about 96 GB of unified memory. These current Apple Silicon Macs have the headroom to run it comfortably:
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See how GPT-oss 120B stacks up against other models on your specific Mac hardware.
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