# Qwen3.8 Flash Next GSQ RCO GGUF

URL: https://interfaze.ai/models/ista-daslabqwen38-flash-next-gsq-rco-gguf

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Qwen3.8 Flash Next GSQ RCO GGUF by ISTA-DASLab, a image-text-to-text model with multimodal capabilities. Understand and compare multimodal features, benchmarks, and capabilities.

## Comparison

| Feature | Qwen3.8 Flash Next GSQ RCO GGUF | Interfaze |
| --- | --- | --- |
| Input Modalities | text, image, video | image, text, audio, video, document |
| Native OCR | No | Yes |
| Long Document Processing | No | Yes |
| Language Support | 201 partial | 162+ |
| Native Speech-to-Text | No | Yes |
| Native Object Detection | No | Yes |
| Guardrail Controls | Yes | Yes |
| Context Input Size | 1M | 1M |
| Tool Calling | Yes | Tool calling supported + built in browser, code execution and web search |

### Scaling

| Feature | Qwen3.8 Flash Next GSQ RCO GGUF | Interfaze |
| --- | --- | --- |
| Scaling | Self-hosted/Provider-hosted with quantization | Unlimited |

[Try Interfaze](https://interfaze.ai/dashboard)[Read the Docs](https://interfaze.ai/docs)

View model card on [Hugging Face](https://huggingface.co/ISTA-DASLab/Qwen3.8-Flash-Next-GSQ-RCO-GGUF)

**Non-uniform GGUF quantizations** of a 512-expert MoE, produced with **GSQ** and **RCO**, with a vision projector for multimodal use.

[![arXiv: GSQ](https://img.shields.io/badge/arXiv-GSQ_2604.18556-b31b1b?logo=arxiv&logoColor=white)](https://arxiv.org/abs/2604.18556) [![arXiv: RCO](https://img.shields.io/badge/arXiv-RCO_2605.00649-b31b1b?logo=arxiv&logoColor=white)](https://arxiv.org/abs/2605.00649) [![GSQ code](https://img.shields.io/badge/code-GSQ-181717?logo=github&logoColor=white)](https://github.com/IST-DASLab/GSQ) [![RCO code](https://img.shields.io/badge/code-RCO-181717?logo=github&logoColor=white)](https://github.com/IST-DASLab/RCO) [![DASLab](https://img.shields.io/badge/DASLab-GitHub-101048?logo=github&logoColor=white)](https://github.com/IST-DASLab) [![license](https://img.shields.io/badge/license-apache--2.0-19a34a)](https://interfaze.ai/models/ista-daslabqwen38-flash-next-gsq-rco-gguf#license)

![Task average vs bit-width](https://huggingface.co/ISTA-DASLab/Qwen3.8-Flash-Next-GSQ-RCO-GGUF/resolve/main/assets/plots/Qwen3.8-Flash-Next-task_avg_vs_avg_bit_width.png)

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## Overview

This repository provides GGUF quantizations of **Qwen3.8-Flash-Next** at four sizes, together with the model's vision projector (`mmproj`) for multimodal use. In contrast to uniform quantization, which applies a single quantization type to all weight tensors, each model here assigns a separate quantization type to every tensor. The assignment is obtained by a gradient-based search that allocates precision according to per-tensor sensitivity, subject to a total size budget. The resulting files are standard GGUF and run unmodified in `llama.cpp`, Ollama, and LM Studio.

A code-specialized variant is released separately as [Qwen3.8-Flash-Next-GSQ-RCO-Coder](https://huggingface.co/ISTA-DASLab/Qwen3.8-Flash-Next-GSQ-RCO-Coder-GGUF), which retains 256 of the 512 routed experts per layer at an effective 1.89 bpw over the original parameters, for a 58.4 GB total.

Flash-Next is a sparse mixture-of-experts model: **512 routed experts per layer across 48 layers**, of which 10 are active per token. The routed expert matrices dominate the parameter count, so they also dominate the size budget: 95% of the searchable weights live in the experts. The search therefore spends most of its freedom there, assigning a quantization type **per layer** (not per expert, which GGUF cannot express).

> **Method summary.** GSQ provides accurate low-bit scalar quantization of each tensor at a given quantization type; RCO assigns the per-tensor quantization types under a size budget. Together they yield a non-uniform GGUF at the requested size.

| Method | Description |
| --- | --- |
| GSQ (Gumbel-Softmax Quantization, paper, code) | Post-training scalar quantization that jointly learns the per-coordinate grid assignments and the per-group scales via a Gumbel-Softmax relaxation. GSQ closes most of the gap between scalar and vector quantization at 2 to 3 bits while remaining deployable in standard scalar formats such as GGUF. |
| RCO (Riemannian Constrained Optimization, paper, code) | Assigns one of K quantization types to each of N tensors under a total size budget. The budget constraint is reformulated as a smooth Riemannian manifold in logit space, which permits gradient-based optimization directly on the task loss while enforcing the budget exactly, without constraint-specific hyperparameter tuning. |

Both methods were developed at the [Deep Algorithms and Systems Lab (DASLab)](https://github.com/IST-DASLab), Institute of Science and Technology Austria.

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## Available files

Files follow the convention **`<model>-GSQ-RCO-<type>.gguf`**, where the suffix names the quantization class; the table lists each file's average bit-width over the transformer weights.

The `mmproj` file carries the vision encoder and projector at BF16; one copy serves all quantizations. Each quantized model ships as **two shards**. The second shard is identical across all four variants: it holds the per-layer n-gram embedding table (`per_layer_token_embd`, 51.2B parameters) at IQ4\_NL. That table is a lookup, not a matmul weight, so it is held at a fixed 4.5 bpw in every build and excluded from the search. It is quantized in the evaluated models, not just the shipped ones.

| Directory | bpw | Shard 1 (weights) | Shard 2 (n-gram) | Total | Notes |
| --- | --- | --- | --- | --- | --- |
| Q2\_0/ | 2.40 | 37.6 GB | 28.8 GB | 66.4 GB | Fastest; avoids lookup-table formats |
| IQ2\_XS/ | 2.50 | 39.2 GB | 28.8 GB | 68.0 GB | Smallest at equal quality |
| IQ3\_XXS/ | 3.00 | 47.0 GB | 28.8 GB | 75.8 GB | Matches the base model on AIME25 |
| IQ3\_S/ | 3.50 | 54.8 GB | 28.8 GB | 83.6 GB | Recommended; matches or exceeds the base model on every task |
| mmproj-Qwen3.8-Flash-Next-BF16.gguf | 16 | 0.91 GB | n/a | 0.91 GB | Vision encoder + projector, for multimodal use |

**Q2\_0** is built for speed. It avoids the quantization formats that rely on large lookup tables: those formats pack more accuracy into a given bit-width, but decoding them costs real time, and on this model that cost dominates inference. Q2\_0 delivers **3.4x the prompt throughput** and **1.9x lower end-to-end latency** than IQ2\_XS at a slightly smaller file size, and its decode rate stays flat across workloads instead of varying with the content. The trade is a little quality: 89.07 task average against 89.16 for IQ2\_XS, and 3.5 points below IQ3\_XXS. Pick it when throughput matters most, and see [Performance](https://interfaze.ai/models/ista-daslabqwen38-flash-next-gsq-rco-gguf#performance) for the measurements.

The IQ3\_S model is the strongest operating point: it matches the base model exactly on AIME25 (100.00), exceeds it on GPQA-Diamond (92.93 against 91.92) and is within 0.57 points on LiveCodeBench v6, at under a quarter of the BF16 size. IQ3\_XXS remains the better choice when memory is tight: it gives up 1.52 points on GPQA-Diamond and 0.57 on LiveCodeBench v6 for 7.8 GB less.

### Memory requirements

Only the first shard holds transformer weights and needs to be resident. The second shard is the n-gram lookup table: it is read sparsely, one row per token, so it can stay memory-mapped on disk and does not need to occupy VRAM. Run with `-lm mmap --lazy-mode on` to get this behaviour, plan for **shard 1 in VRAM**, and keep shard 2 on an SSD so the paging stays cheap.

| Model | Must be resident (shard 1) | Can stay on disk (shard 2) | Total download |
| --- | --- | --- | --- |
| Q2\_0 | 37.6 GB | 28.8 GB | 66.4 GB |
| IQ2\_XS | 39.2 GB | 28.8 GB | 68.0 GB |
| IQ3\_XXS | 47.0 GB | 28.8 GB | 75.8 GB |
| IQ3\_S | 54.8 GB | 28.8 GB | 83.6 GB |

Add headroom for the KV cache and the vision projector (0.91 GB) if used. Keeping the n-gram table in RAM rather than on disk removes the paging cost entirely and is worth it where memory allows.

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## Performance

Measured with `llama.cpp` over 55 prompts spanning eleven categories (coding, humanities, math, QA, RAG, reasoning, STEM, writing, multilingual, summarization, roleplay).

| Model | Prompt t/s | Decode t/s | Avg latency |
| --- | --- | --- | --- |
| Q2\_0 | 367.49 | 93.79 | 6.70 s |
| IQ2\_XS | 108.19 | 70.30 | 12.68 s |

![Prefill throughput by category](https://huggingface.co/ISTA-DASLab/Qwen3.8-Flash-Next-GSQ-RCO-GGUF/resolve/main/assets/plots/Qwen3.8-Flash-Next-prefill_throughput.png)

The gap comes from the quantization formats rather than the size: the two files differ by only 1.6 GB, and Q2\_0 is the smaller of the two. Q2\_0's decode rate is also far more stable across categories, 92.5 to 94.5 t/s (a 2.0 t/s spread), where IQ2\_XS swings from 49.4 to 94.5 t/s (a 45.1 t/s spread), because the lookup cost varies with how much of each layer a request touches.

The prefill advantage is uneven, and largest where prompts are long: 9.6x on RAG, 6.8x on writing and 6.2x on coding. On short-prompt, reasoning-heavy categories the two are level or Q2\_0 is marginally behind (0.8x to 0.9x on stem, math and reasoning), where prefill is too brief for the format's decoding cost to matter.

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## Results

All models are evaluated against the **BF16** base model. We report the average over five zero-shot tasks (arc\_easy, arc\_challenge, hellaswag, winogrande, piqa), recovery (zero-shot average relative to BF16), and three reasoning and generation benchmarks: **AIME25**, **GPQA-Diamond**, and **LiveCodeBench v6**. Task average is the mean of the three. Sizes are the full download, including the n-gram shard; the bit-width column is the average over the transformer weights, which is what the search controls.

| Variant | bpw | GB | ZS avg↑ | recovery | AIME25↑ | GPQA-D↑ | LCB v6↑ | Task avg↑ |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| BF16 | 16.00 | 354 | 76.94 | 100.0% | 100.00 | 91.92 | 87.43 | 93.12 |
| GSQ-RCO Q2\_0 | 2.40 | 66.4 | 78.00 | 101.4% | 96.67 | 89.39 | 81.14 | 89.07 |
| GSQ-RCO IQ2\_XS | 2.50 | 68.0 | 77.16 | 100.3% | 96.67 | 87.37 | 83.43 | 89.16 |
| GSQ-RCO IQ3\_XXS | 3.00 | 75.8 | 77.23 | 100.4% | 100.00 | 91.41 | 86.29 | 92.57 |
| GSQ-RCO IQ3\_S | 3.50 | 83.6 | n/a | n/a | 100.00 | 92.93 | 86.86 | 93.26 |

All three models exceed the BF16 base on the zero-shot average (100.3% to 101.4%), which is common for careful low-bit quantization on these five tasks: the differences are within roughly one standard error and should be read as parity rather than improvement. The same applies where IQ3\_S exceeds the base on GPQA-Diamond and on the task average: recoveries slightly above 100% reflect benchmark variance, not a model that is better than the one it was quantized from. The reasoning and generation benchmarks separate the models far more clearly.

At 3.00 bpw, IQ3\_XXS reaches **99.4%** of the base model's task average (92.57 against 93.12) while being **4.7x smaller** (75.8 GB against 354 GB). It matches the base exactly on AIME25 (100.00), and trails by 0.51 on GPQA-Diamond and 1.14 on LiveCodeBench v6. At 2.50 bpw, IQ2\_XS retains 95.7% of the task average at 68.0 GB, and the smallest build, Q2\_0, holds 96.67 on AIME25 at 66.4 GB, a 5.3x reduction.

The two sub-2.5 bpw builds land within 0.1 points of each other on task average despite different allocations: Q2\_0 is stronger on GPQA-Diamond (89.39 against 87.37) while IQ2\_XS is stronger on LiveCodeBench v6 (83.43 against 81.14).

![AIME25 vs bit-width](https://huggingface.co/ISTA-DASLab/Qwen3.8-Flash-Next-GSQ-RCO-GGUF/resolve/main/assets/plots/Qwen3.8-Flash-Next-aime25_vs_avg_bit_width.png)

![GPQA-Diamond vs bit-width](https://huggingface.co/ISTA-DASLab/Qwen3.8-Flash-Next-GSQ-RCO-GGUF/resolve/main/assets/plots/Qwen3.8-Flash-Next-gpqa_diamond_vs_avg_bit_width.png)

![LiveCodeBench v6 vs bit-width](https://huggingface.co/ISTA-DASLab/Qwen3.8-Flash-Next-GSQ-RCO-GGUF/resolve/main/assets/plots/Qwen3.8-Flash-Next-lcb_vs_avg_bit_width.png)

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## Usage

Both shards must be downloaded; `llama.cpp` loads the split automatically when given the first one.

### llama.cpp

```
hf download <this-repo> --include "IQ3_XXS/*" --local-dir .

llama-cli -m IQ3_XXS/Qwen3.8-Flash-Next-GSQ-RCO-IQ3_XXS-00001-of-00002.gguf \
  -lm mmap --lazy-mode on \
  -p "Explain mixed-precision quantization." -ngl 99
```

`-lm mmap --lazy-mode on` keeps the n-gram table memory-mapped on disk instead of loading it into memory, which removes 28.8 GB from the resident footprint. See [Memory requirements](https://interfaze.ai/models/ista-daslabqwen38-flash-next-gsq-rco-gguf#memory-requirements).

### Strata Engine

Many users report strong results with [Strata](https://github.com/Niko1221/Strata), a third-party engine that runs these GGUFs on a single NVIDIA GPU from 8 GB of VRAM, with a one-click installer and an OpenAI-compatible endpoint on localhost.

### Vision (multimodal)

```
hf download <this-repo> mmproj-Qwen3.8-Flash-Next-BF16.gguf --local-dir .

llama-mtmd-cli -m IQ3_XXS/Qwen3.8-Flash-Next-GSQ-RCO-IQ3_XXS-00001-of-00002.gguf \
  --mmproj mmproj-Qwen3.8-Flash-Next-BF16.gguf \
  -lm mmap --lazy-mode on \
  --image photo.jpg -p "Describe this image."
```

The projector was converted directly from the base checkpoint and is shared by all four quantizations.

### Ollama

```
ollama run hf.co/<this-repo>   # pick the directory matching your memory budget
```

### LM Studio

Search the repo name, then pick a `GSQ-RCO-*` build from the file list.

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## Quantization procedure

1.  **Per-tensor database.** Each weight tensor is quantized at every candidate GGUF quantization type with GSQ, yielding a searchable database of quantized tensor variants.
2.  **RCO search.** The budget-constrained Riemannian search assigns one quantization type per tensor such that the whole-file average bit-width meets the target.
3.  **Assembly.** The selected per-tensor variants are stitched into a single standard GGUF file.

For this model the search covers **352 tensors**: the 304 dense tensors (attention, SSM projections, shared experts, embeddings, output head) and the 48 fused routed-expert matrices, one per layer. Two classes draw on separate quantization ladders, because the routed experts sit at a much lower bit-width than the dense path at any given budget. `ffn_down_exps` searches over a much smaller ladder than the other expert matrices. Its 640 rows are not divisible by 256, which rules out every block-256 K and I quant format and leaves only Q2\_0 (block 64) and IQ4\_NL (block 32). In the two smaller builds every layer lands on Q2\_0; in IQ3\_XXS the search lifts 18 of the 48 layers to IQ4\_NL.

Reference implementations: **GSQ** at [IST-DASLab/GSQ](https://github.com/IST-DASLab/GSQ) and **RCO** at [IST-DASLab/RCO](https://github.com/IST-DASLab/RCO).

### Reproducibility artifacts

Each released GGUF ships the files needed to audit how it was built:

| File | Contents |
| --- | --- |
| tensor-allocation/<model>.rco-allocation.txt | The quantization type assigned to every tensor in that file, with a quant-type histogram and the target bit-width. This is the RCO search result, so the allocation can be inspected without opening the model. |

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## Citation

If you use these models or methods, please cite both papers:

```
@article{gsq2026,
  title  = {GSQ: Highly-Accurate Low-Precision Scalar Quantization for LLMs via Gumbel-Softmax Sampling},
  author = {Dadgarnia, Alireza and Tabesh, Soroush and Nikdan, Mahdi and Helcig, Michael and Kurtic, Eldar and Kleinegger, Maximilian and Alistarh, Dan},
  journal= {arXiv preprint arXiv:2604.18556},
  year   = {2026}
}
@article{rco2026,
  title  = {Model Compression with Exact Budget Constraints via Riemannian Manifolds},
  author = {Helcig, Michael and Alistarh, Dan},
  journal= {arXiv preprint arXiv:2605.00649},
  year   = {2026}
}
```

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## Acknowledgements

We thank [Verda](https://verda.com/) and Scientific Computing at the Institute of Science and Technology Austria for providing the compute resources used to produce these models.

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## License

These quantized weights inherit the license of the base model (**Qwen3.8-Flash-Next**). The GSQ-RCO tooling is released by the Deep Algorithms and Systems Lab under its repository license.

## Want more deterministic results?

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