Qwen3.8-27B-AWQ

A mixed-precision quantization of the language path in Qwen/Qwen3.8-27B: W4A16 asymmetric AWQ on the MLP and attention projections, int8 group quantization on the Gated DeltaNet input projections. The vision tower is left in source precision, so this is still a multimodal checkpoint. Images run through an unquantized encoder into a quantized decoder.

Recipe, calibration builder, evaluation protocol and raw results: github.com/nicosuter/Qwen3.8-27B-AWQ

Provenance

run-metadata.json, pip-freeze.txt, the exact calibration manifest.jsonl and its SHA256 ship alongside the weights here. If you want to reproduce or audit any of this, start there and in the repository, not from this card.

What is and is not quantized

These modules stay in source precision:

• the vision tower (visual/vision)
• the MTP head
• Gated DeltaNet in_proj_a and in_proj_b
• lm_head

The Gated DeltaNet in_proj_qkv and in_proj_z projections are int8 rather than 4-bit. Everything else that is a Linear gets W4A16.

Calibration data

Revisions: Open-SWE ad4805a, Lambda b92885e, Nemotron 74e23eb, Cauldron 847a98a, FineWeb-Edu 87f0914.

Evaluation

Across five counted suites this checkpoint is within two tenths of a point of Qwen/Qwen3.8-27B-FP8 overall. The suites cover executable coding, tool calls and two kinds of multimodal input, plus a long-context check that is reported but no longer counted. Nothing here tests agentic use. This model card will be expanded with further evals in the near future.

Both checkpoints were scored on the same items in the same order. Recovery is the AWQ score divided by the FP8 one, averaged across the counted suites with the geometric mean. Intervals are a bootstrap over 20,000 resamples, clustered by item. Every suite ran over its whole item set on H200 NVL cards. GPQA Diamond, LiveCodeBench and MMMU-Pro ran twice per checkpoint and their rows pool both passes; the other three ran once. The protocol is in EVAL.md.

BFCL is the static split of gorilla-llm/Berkeley-Function-Calling-Leaderboard: simple through parallel-multiple, irrelevance, and their six live counterparts, which are real user-submitted prompts shipped as static data. The executable, REST, multi-turn and chatable categories need the Gorilla simulators, so they are excluded, and the Java, JavaScript and SQL splits have answers this Python matcher cannot read. Tools are passed to the model natively. Neither checkpoint produced a malformed tool call.

LiveCodeBench v6 is pass@1: an item counts only if it passes every public and private test. Multimodal is DocVQA, ChartQA and TextVQA, 200 items each, scored with their published metrics. MMMU-Pro is the ten-option config across thirty subjects.

RULER is synthesized here at 4k, 32k and 128k rather than the upstream benchmark, so its scores compare these two checkpoints and nothing else. It no longer counts toward the macro. Its 150 retrieval items score between 99.07 and 100.00 on both checkpoints, which leaves the suite score to the 50 counting items, and those turn on whether the model runs out of output budget before it finishes transcribing the list. That measures the window rather than long-context quality. RULER still runs as a smoke check.

No suite's interval excludes zero. MMMU-Pro comes closest: its interval runs from -2.17 to exactly zero.

The same protocol, against the same baseline arm, also scored four other published AWQ quantizations of this model. Their results and the quantization scheme each one uses are in results/2026-08-23-published-quants; the intervals there are wide enough that most of those checkpoints do not separate from each other, and the write-up says so.

What this does not cover

• No agentic suite.
• Repeat passes move these numbers by more than the numbers themselves. MMMU-Pro recovered 97.45% on its first pass and 99.77% on its second, same two checkpoints, nothing changed in between. The row above pools both. The three suites that ran once carry the same noise with no way to see it.
• 91% of items score the same on both checkpoints, mostly at ceiling, so the effective sample is far smaller than the item counts suggest. On BFCL, 124 items improve and 122 regress, and the +0.06 is what is left once they cancel.
• Nothing here resolves to a tenth of a point, and the small suites resolve worst: GPQA Diamond's interval is +/-2.3 points around a measured -1.26, and LiveCodeBench's +/-2.9 around +1.43.
• RULER truncated 15 baseline and 12 candidate items at the 262,144-token window even with the output cap removed. Its 128k counting task is left out: one pass over the word list needs more output than the window leaves, and it scored zero on both checkpoints.

What this cost

39 H200-hours in total. The first pass over both checkpoints and every suite took 25 of them, in one job on 4x H200 over 6h13. The second pass over GPQA Diamond, LiveCodeBench and MMMU-Pro took the other 14, on 8x H200 over 1h48.

Note to other quantizers: a paired quality check against another model is a few GPU hours on four cards. If you publish a quantization, you can afford to measure it rather than inherit the upstream model's numbers.

Usage

vLLM

vllm serve nicosuter/Qwen3.8-27B-AWQ \
  --max-model-len 262144 \
  --reasoning-parser qwen3 \
  --enable-auto-tool-choice \
  --tool-call-parser qwen3_coder

The weights are 21.5 GB before any KV cache. To save VRAM, drop what you are not using: --limit-mm-per-prompt '{"image": 0}' for the vision tower, and the 0.85 GB MTP shard if you are not running speculation.

Use the upstream generation policy: thinking enabled, temperature=1.0, top_p=0.95, top_k=20, min_p=0, no presence penalty, repetition penalty 1.0. Qwen warns that greedy decoding degrades thinking-mode output and can trigger repetition loops, and that warning carries over here.

MTP / speculative decoding

The 15 MTP tensors are copied unchanged from the pinned source checkpoint into a dedicated BF16 shard after AWQ serialization. Native speculation can be enabled with:

--speculative-config '{"method":"mtp","num_speculative_tokens":3}'

Limitations

• Long context is only tested synthetically, and the synthetic test turned out weak enough that we stopped counting it. RULER at 4k, 32k and 128k found no difference. But the recurrent path is quantized at 8 bits, and error in a recurrent state builds up along the sequence instead of staying bounded per token. Finding a planted string in generated text does not probe that.
• An unquantized vision tower does not make multimodal output safe: image tokens still pass through a quantized decoder. On document, chart and scene text the multimodal suite found no difference. MMMU-Pro, which runs the reasoning after perception through the quantized path, moved most between repeat passes, so its number is the least settled one here.

License

Apache 2.0, following the upstream model.