GPT-OSS 20B needs ~26.1 GB VRAM. RTX PRO 6000 Blackwell Server Edition 96GB has 96.0 GB. With Q4_K_M quantization, expect ~240 tok/s.
Operating mode
Interactive favors responsiveness, while light API and scale-out lean harder on serving readiness. The fit stays the same, but the recommendation lens changes.
Current mode
Balanced
Balanced for general local use. Keeps the ranking neutral across personal and serving workflows.
Select quantization to explore
Fit status
Runs well
Decode
257.5 tok/s
TTFT
752 ms
Safe context
128K
Memory
26.1 GB / 96.0 GB
This setup is broadly balanced for this model.
No major red flags
This recommendation has enough memory headroom and acceptable estimated speed for the selected workload.
| Workload | Grade | Fit | Decode | TTFT | Context |
|---|---|---|---|---|---|
| Chat | S | Runs well | 257.5 tok/s | 410 ms | 128K |
| Coding | S | Runs well | 239.6 tok/s | 808 ms | 128K |
| Agentic Coding | S | Runs well | 257.5 tok/s | 1093 ms | 128K |
| Reasoning | S | Runs well | 257.5 tok/s | 888 ms | 128K |
| RAG | S | Runs well | 257.5 tok/s | 1367 ms | 128K |
Inference speed
Estimated decode speed (tokens/sec) for GPT-OSS 20B at Q4_K_M across popular GPUs and Apple Silicon, using the fastest local runtime per device. Fastest is RTX 5090 32GB at ~231 tok/s. Speed is memory-bandwidth bound, so cards that fit the whole model in VRAM run far faster than ones that offload to system RAM.
| GPU / Mac | Memory | Quant | Speed (tok/s) | Fits? |
|---|---|---|---|---|
| 32 GB | Q4_K_M | 230.5 | Fits | |
| 24 GB | Q4_K_M | 147.1 | Fits | |
How GPT-OSS 20B (21B params) fits at each quantization level on RTX PRO 6000 Blackwell Server Edition 96GB (96.0 GB usable).
| Quant | Bits | VRAM | Quality | Fit |
|---|---|---|---|---|
Q2_K | 2 | 8.2 GB | Low | A78 |
Q3_K_S | 3 | 10.3 GB | Low | A78 |
NVFP4 | 4 |
Copy-paste commands to run GPT-OSS 20B on your machine.
Run
ollama run gpt-ossYour hardware
| Model | Params | Grade | Decode | Capabilities |
|---|---|---|---|---|
| 123B | S | 19.4 tok/s | ||
| 30.5B |
Yes, RTX PRO 6000 Blackwell Server Edition 96GB can run GPT-OSS 20B with a S grade (Runs well). Expected decode speed: 239.6 tok/s.
GPT-OSS 20B (21B parameters) requires approximately 26.1 GB of memory with Q4_K_M quantization.
The recommended quantization for GPT-OSS 20B is Q4_K_M, which balances quality and memory efficiency.
On RTX PRO 6000 Blackwell Server Edition 96GB, GPT-OSS 20B achieves approximately 239.6 tokens per second decode speed with a time-to-first-token of 808ms using Q4_K_M quantization.
For coding workloads, GPT-OSS 20B on RTX PRO 6000 Blackwell Server Edition 96GB receives a S grade with 239.6 tok/s and 128K context.
On RTX PRO 6000 Blackwell Server Edition 96GB, GPT-OSS 20B can safely use up to 128K tokens of context. The model's official context limit is 128K, but available memory constrains the safe maximum.
Paste this snippet into any page to show a live fit card.
<iframe src="https://willitrunai.com/embed/gpt-oss-20b-on-rtx-pro-6000-blackwell-server-96gb" width="400" height="180" frameborder="0" style="border:none;border-radius:12px;overflow:hidden;" title="Will It Run AI — fit result"></iframe>
Preview:
| 24 GB |
| Q4_K_M |
| 132.7 |
| Fits |
| 24 GB | Q4_K_M | 125.8 | Fits |
Mac Studio M3 Ultra 256GB | 256 GB | Q4_K_M | 106.9 | Fits |
Mac Studio M2 Ultra 128GB | 128 GB | Q4_K_M | 89.1 | Fits |
Mac Studio M1 Ultra 128GB | 128 GB | Q4_K_M | 84.5 | Fits |
| 16 GB | Q4_K_M | 68.2 | Heavy offload |
MacBook Pro M4 Max 128GB | 128 GB | Q4_K_M | 66.0 | Fits |
MacBook Pro M4 Max 64GB | 64 GB | Q4_K_M | 66.0 | Fits |
MacBook Pro M3 Max 64GB | 64 GB | Q4_K_M | 46.1 | Fits |
MacBook Pro M1 Max 64GB | 64 GB | Q4_K_M | 42.2 | Fits |
MacBook Pro M4 Pro 48GB | 48 GB | Q4_K_M | 40.4 | Fits |
| 12 GB | Q4_K_M | 24.2 | Too big |
| 12 GB | Q4_K_M | 15.2 | Too big |
| 8 GB | Q4_K_M | 5.7 | Too big |
Estimates for single-stream decoding at Q4_K_M; real tokens/sec varies with prompt length, context, batch size, and runtime build. Prompt processing (prefill) is faster than the decode figures shown here.
11.8 GB |
| Medium |
| A78 |
Q4_K_M | 4 | 12.8 GB | Medium | A78 |
Q5_K_M | 5 | 15.1 GB | High | A78 |
Q6_K | 6 | 17.2 GB | High | A79 |
Q8_0 | 8 | 22.5 GB | Very High | A79 |
F16Best for your GPU | 16 | 43.1 GB | Maximum | A84 |
| 202.8 tok/s |
| 27B | S | 88 tok/s |
| 27B | S | 88.2 tok/s |
| 122B | S | 53.9 tok/s |