---
base_model: upstage/Solar-Open2-250B
base_model_relation: quantized
library_name: vllm
pipeline_tag: text-generation
language:
  - en
  - ko
  - ja
tags:
  - quantization
  - nvfp4
  - vllm
  - moe
  - nota
---

# Solar Open2 250B — Nota NVFP4

[Nota AI](https://www.nota.ai/) presents a 4-bit quantized release of
[Upstage](https://www.upstage.ai/)'s
[Solar Open2 250B](https://huggingface.co/upstage/Solar-Open2-250B), produced with
Nota AI's proprietary quantization technology specialized for Mixture-of-Experts (MoE)
large language models.

## Highlights

- **NVFP4 (4-bit float, W4A4)** — `group_size=16`, packed in the `llm-compressor`
  (compressed-tensors) format for direct serving in
  [vLLM](https://github.com/vllm-project/vllm). Both weights and activations are
  quantized to 4-bit floating point.
  - > **Requires NVIDIA Blackwell.** NVFP4 relies on the FP4 tensor cores introduced in
    > the Blackwell architecture (e.g. B200 / GB200), so inference must run on a
    > Blackwell-class GPU. Earlier architectures (Hopper, Ada, Ampere) do not support
    > NVFP4 execution.
- **Nota AI's proprietary MoE quantization framework.** This release is built upon a
  suite of techniques developed by Nota AI to preserve model quality under aggressive
  low-bit quantization of MoE architectures:
  - A MoE-specialized calibration-dataset construction method, which achieved
    **1st place across all tracks** at the NVIDIA Nemotron Hackathon.
  - [**DREAM-MoE**](https://openreview.net/pdf?id=Wyhqwjl51A) and
    [**SRA-MoE**](https://openreview.net/pdf?id=H0NoX02erJ), two quantization algorithms
    proposed by Nota AI (published at the *ICML 2026 Workshop on AdaptFM*), which
    preserve MoE routing decisions and align expert-routing behavior throughout the
    quantization process.

## License
This repository contains both model weights and code,
which are licensed under different terms:

1. MODEL WEIGHTS (*.safetensors)
   The Upstage Solar License is based on the permissive Apache License 2.0 with specific mandatory conditions to support the Solar ecosystem. 
   
   **Key requirements for Derivative AI Models** (create / train / fine-tune / distill / improve using Solar Open 2): 
   - Naming: prefix your model name with "Solar" (e.g., Solar-MyModel-v1).
   - Attribution: prominently display "Built with Solar" in related public-facing materials.
   - Notice: include a copy of the Upstage Solar License with your derivative model.

2. CODE (*.py, *.json, *.jinja files)
   Licensed under **Apache License 2.0**
   See: https://www.apache.org/licenses/LICENSE-2.0

## Performance

### Weight footprint

| Precision          | Weight footprint |
| ------------------ | :--------------: |
| BF16               |     500.6 GB     |
| Nota NVFP4         |     153.3 GB     |

### Benchmarks

| Benchmark               |       BF16       | Nota NVFP4 |
| ----------------------- | :--------------: | :---------------: |
| Tau2-Bench              |      75.20       |       75.08       |
| HLE                     |      27.88       |       27.66       |
| GPQA Diamond            |      86.26       |       85.45       |
| IFBench                 |      80.00       |       81.02       |
| LiveCodeBench (v5–v6)   |      87.03       |       88.55       |
| MMLU-Pro                |      86.19       |       86.15       |
| AIME 2026 (EN)          |      95.67       |       96.67       |
| IFEval (EN)             |      94.09       |       92.61       |
| HMMT                    |      92.05       |       90.15       |
| KMMLU-Pro               |      78.38       |       77.93       |
| HAE-RAE Bench v1.1      |      73.84       |       72.84       |
| AIME (KO)               |      97.67       |       97.00       |
| KBL                     |      75.51       |       75.40       |
| KBank-MMLU              |      80.80       |       80.68       |
| KorMedMCQA              |      92.99       |       93.05       |
| **Avg.**                |    **81.57**     |     **81.35**     |

## Usage

This model is packed in the NVFP4 (compressed-tensors) format and can be served directly
with vLLM on a **Blackwell-class GPU**:

```bash
vllm serve nota-ai/Solar-Open2-250B-Nota-NVFP4 \
  --tensor-parallel-size 4 \
  --trust-remote-code
```

- Set `--tensor-parallel-size` according to the number of GPUs available in your serving environment.

- For reasoning and tool-calling, use the reasoning parser and tool parser provided in the original [upstage/Solar-Open2-250B](https://huggingface.co/upstage/) model card.

- See the original model card for the prompt format, parser configuration, and further details.

## Citation
```bibtex
@inproceedings{park2026dreammoe,
  title     = {{DREAM-MoE}: Downstream Routing Error-Aware Margin-Preserving Quantization for Mixture-of-Experts Large Language Models},
  author    = {Park, Hancheol and Lee, Geonho and Kim, Tae-Ho},
  booktitle = {ICML 2026 Workshop on Resource-Adaptive Foundation Model Inference (AdaptFM)},
  year      = {2026},
  url       = {https://openreview.net/forum?id=Wyhqwjl51A},
}

@inproceedings{lee2026sramoe,
  title     = {{SRA-MoE}: Output-Aware Selective Router Alignment for MoE Quantization},
  author    = {Lee, Geonho and Park, Hancheol and Lee, Seunghyun and Choi, Jungwook and Kim, Tae-Ho},
  booktitle = {ICML 2026 Workshop on Resource-Adaptive Foundation Model Inference (AdaptFM)},
  year      = {2026},
  url       = {https://openreview.net/forum?id=H0NoX02erJ},
}
```