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Yes. gpt-oss 20B (MoE, MXFP4) fits in fast memory on RTX 5090 32GB at MXFP4 (15.1 GB needed, 31.5 GB usable), about 223 tok/s (estimate).
Hardware: RTX 5090 32GB · Model: gpt-oss 20B (MoE, MXFP4)
RTX 5090 32GB has 32 GB of VRAM and 1792 GB/s of memory bandwidth. The checker holds back 0.5 GB of VRAM for the driver and assumes 16 GB of system RAM, so fast memory usable by Ollama is 31.5 GB. Partial offload may also use 60% of that system RAM. gpt-oss 20B (MoE, MXFP4) (20.9B, 3.6B active, OpenAI) at MXFP4 is a 14 GB download and needs 15.1 GB with headroom for about 8k tokens.
| Best quant | MXFP4 |
|---|---|
| Download size | 14 GB |
| Memory needed | 15.1 GB |
| Usable fast memory | 31.5 GB |
| Fit | fits in fast memory |
| Estimated speed | ~223 tok/s (estimate) |
| Command | ollama run gpt-oss:20b |
Estimates, not benchmarks. Model sizes are ollama.com download sizes; memory needed adds headroom for ~8k tokens of context; speeds are rough figures from memory bandwidth. Data updated 2026-10-23.
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