Controlled comparison

Q4_K_M vs Q8_0: does the bigger quant buy anything?

Is it worth spending the extra memory on the Q8_0 artifact of Qwen3.6-35B-A3B for chat and JSON automation on Strix Halo?

What was held fixed

Same unit, same Vulkan backend build, same frozen corpora, single stream, reasoning off. Only the model artifact differs (both pinned by hash).

Metric Q4_K_M (20 GB) Q8_0 (35 GB)
Inter-token latency, median (decode pace) 15.9ms/tokenmedian over valid requests · lab_repeated · evidence 18.7ms/tokenmedian over valid requests · lab_repeated · evidence
Strict-JSON task success 100.0% of requestsshare of all issued requests · lab_repeated · evidence 100.0% of requestsshare of all issued requests · lab_repeated · evidence

How to read this

On the workloads these gates can see, the bigger artifact bought nothing: task success is identical, and Q8_0 decodes slower. If your workload resembles these — everyday chat and strict-JSON extraction — the memory is better spent on context.

Limits

Quality gates here are format/JSON/repetition classes — a quant difference could surface on harder reasoning or multilingual generation these workloads do not probe. Negative result, scoped to what was measured.

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