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 RX 7900 XTX 24GB has 22 GB usable, so it doesn't fit, even at its smallest quantization.
| Quantization | File size | Memory | Generation | First token | Source |
|---|---|---|---|---|---|
| MXFP4 | 63.4 GB | Doesn't fit | Won't run | — | — |
All models on the AMD RX 7900 XTX 24GB · 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.