Qwen3.6-27B NVFP4 GGUF
NVFP4 GGUF quantizations of Qwen/Qwen3.6-27B, produced for use with llama.cpp.
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The FFN tensors are quantized to NVFP4 (NVIDIA's 4-bit float with E4M3 block scale), repacked from mmangkad/Qwen3.6-27B-NVFP4 (NVIDIA ModelOpt calibration). The remaining tensors (attention projections, SSM linear_attn blocks, embeddings, output) use a conventional GGUF quant — three variants are provided.
Why NVFP4? On NVIDIA Blackwell GPUs (RTX 50-series, B100/B200), llama.cpp uses native NVFP4 tensor-core MMA kernels (added in llama.cpp #22196) for the FFN matmul — the dominant compute cost during inference. On older GPUs the path falls back to
dp4a/MMQ kernels, where these GGUFs run but offer no perf advantage over standard K-quants.
Files
| File | Size | FFN | Other tensors | When to pick |
|---|---|---|---|---|
Qwen3.6-27B-NVFP4-Q4_K_M.gguf |
15 GB | NVFP4 | Q4_K_M | Recommended. Fastest serving throughput on Blackwell + smallest VRAM footprint |
Qwen3.6-27B-NVFP4-Q8_0.gguf |
19 GB | NVFP4 | Q8_0 | Higher precision attention/embeddings if you have the VRAM |
Qwen3.6-27B-NVFP4-BF16.gguf |
28 GB | NVFP4 | BF16 | Max quality (preserves source precision for non-FFN tensors); slower in practice — only pick if you need bit-for-bit source fidelity |
mmproj-Qwen3.6-27B-F16.gguf |
889 MB | — | F16 vision tower | Required for image/video input — reusable with any Qwen3.6-27B GGUF, not NVFP4-specific |
Performance
Measured on an NVIDIA RTX 5090 (32 GB, Blackwell, sm_120), llama.cpp build c84e6d6db.
Batched serving (llama-batched-bench, 512 in / 128 out per request)
NVFP4-Q4_K_M beats stock Q4_K_M on total serving throughput at every parallel batch size we tested (+9 / +0 / +8 / +2% at 1 / 4 / 8 / 16 sequences), with the largest token-generation wins at single stream (+12%) and 8 parallel sequences (+14%). It also uses less VRAM (14.7 vs 16.3 GiB), leaving more room for KV cache.
Variant comparison (same hardware)
| Variant | Size | PP512 (tok/s) | TG64 (tok/s) |
|---|---|---|---|
NVFP4-Q4_K_M |
14.72 GiB | 2865 | 64 |
NVFP4-Q8_0 |
18.65 GiB | 3346 | 64 |
NVFP4-BF16 |
27.19 GiB | 1403 | 49 |
The Q4_K_M variant is the speed/efficiency winner. The BF16 variant is included for completeness but pays a real bandwidth cost — only pick it if you need maximum precision on the non-FFN tensors and don't care about throughput.
Usage
Text-only (CLI)
llama-cli -m Qwen3.6-27B-NVFP4-Q8_0.gguf -ngl 999 -c 8192 -p "Your prompt here"
Multimodal (server, vision + text)
llama-server \
-m Qwen3.6-27B-NVFP4-Q8_0.gguf \
--mmproj mmproj-Qwen3.6-27B-F16.gguf \
-ngl 999 -c 32768 \
--host 0.0.0.0 --port 8080
Then POST to /v1/chat/completions with image content blocks — see the llama.cpp multimodal docs.
Recommended sampler
Qwen3.6 is a thinking model. Default chat template enables <think> blocks. For non-thinking usage pass --reasoning off (in llama-cli) or set chat_template_kwargs.enable_thinking=false in the API.
About the architecture
Qwen3.6-27B is a hybrid attention + SSM dense model: every 4th layer is conventional attention; the remaining 48 of 64 layers use Mamba-style linear_attn blocks. The NVFP4 source from mmangkad keeps the SSM in_proj_* projections and standard attention projections at higher precision — only the FFN matmul (192 tensors) is NVFP4. The variants above differ only in how those non-FFN tensors are stored.
Sources & credits
- Base model: Qwen/Qwen3.6-27B by Alibaba Qwen team — Apache 2.0
- NVFP4 calibration source: mmangkad/Qwen3.6-27B-NVFP4 (NVIDIA ModelOpt v0.42.0)
- mmproj source: official BF16 weights from
Qwen/Qwen3.6-27B - Tooling: llama.cpp
convert_hf_to_gguf.pyandllama-quantize
License
Apache 2.0, inherited from the upstream model.