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Yes. gpt-oss 20B (MoE, MXFP4) fits in fast memory on RTX 4090 24GB at MXFP4 (15.1 GB needed, 23.5 GB usable), about 125 tok/s (estimate).
Hardware: RTX 4090 24GB · Model: gpt-oss 20B (MoE, MXFP4)
RTX 4090 24GB has 24 GB of VRAM and 1008 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 23.5 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 | 23.5 GB |
| Fit | fits in fast memory |
| Estimated speed | ~125 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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