GPT-OSS 120B is a 116.83B-parameter mixture-of-experts model (5.1B active per token). At MXFP4 it needs about 64.1 GB of memory. The AMD Ryzen AI Max+ 395 128GB (Strix Halo) has 119 GB usable, so it fits entirely in memory. Expect about 52 tokens/sec (46–58), with the first token after 0.4 s for a short prompt. This estimate is based on community benchmarks of this exact setup.
| Quantization | File size | Memory | Generation | First token | Source |
|---|---|---|---|---|---|
| MXFP4 | 63.4 GB | Fits | 52 tok/s | 0.4 s | Measured |
All models on the AMD Ryzen AI Max+ 395 128GB (Strix Halo) · GPT-OSS 120B on all hardware
Estimates for a short prompt on a single device. Measured numbers come from community benchmarks (r/LocalLLaMA, localscore.ai and more); others are derived from similar setups or projected from specs. Open source on GitHub.