Known-issues sheets for local language models Rev 0.1.0 · reviewed every 7 days

Model datasheet · Qwen3

Qwen3 30B-A3B

A mixture-of-experts model: 30B of knowledge, but only ~3B active per token, so it runs fast on machines that can hold it. The best quality-per-second story on 32GB Macs.

Vendor
Alibaba
Architecture
MoE · 30.5B total / ~3.3B active
Context
131,072 tokens
License
Apache-2.0
Released
2025-04-29
Vision
No

→ GGUF (llama.cpp / LM Studio / Ollama) → MLX (Apple Silicon)

§1 Characteristics by quantization band

Q2–Q3 — 2–3 bit

11GB weights · e.g. IQ3_XXS , Q3_K_M + KV: 768MB at 8K · 3GB at 32K · 12GB at 128K
Math & reasoning 4/10
data checked Aug 2026
  • quant-degradation-community — degradation reports @ Q3_K_M · aggregated · 2026-08-30

    Editorial derivation: ≤3-bit hits MoE expert weights hard; math cliff applies.

Coding 5/10
data checked Aug 2026
  • quant-degradation-community — degradation reports @ Q3_K_M · aggregated · 2026-08-30

    Editorial derivation: usable but error-prone at 3-bit.

Tool calling / agentic 4/10
data checked Aug 2026
  • quant-degradation-community — community consensus @ Q3_K_M · aggregated · 2026-08-30

    Editorial derivation: malformed tool arguments become common at ≤3-bit.

Q4–Q5 — 4–5 bit

17GB weights · e.g. Q4_K_M , Q5_K_M , mlx-4bit + KV: 768MB at 8K · 3GB at 32K · 12GB at 128K
Math & reasoning 7/10
data checked Aug 2026
  • quant-degradation-community — KLD delta vs bf16 @ Q4_K_M · aggregated · 2026-08-30

    Editorial derivation: MoE models tolerate 4-bit well; small loss vs full band.

Coding 7/10
data checked Aug 2026
  • quant-degradation-community — KLD delta vs bf16 @ Q4_K_M · aggregated · 2026-08-30

    Editorial derivation: small loss vs full band at Q4_K_M.

Tool calling / agentic 6/10
data checked Aug 2026
  • quant-degradation-community — community consensus @ Q4_K_M · aggregated · 2026-08-30

    Editorial derivation: occasional argument-format slips at 4-bit.

Instruction following 7/10
data checked Aug 2026
  • quant-degradation-community — community consensus @ Q4_K_M · aggregated · 2026-08-30

    Editorial derivation: IF not quant-sensitive.

Q6–Q8 — 6–8 bit

24GB weights · e.g. Q6_K + KV: 768MB at 8K · 3GB at 32K · 12GB at 128K
Math & reasoning 8/10
data checked Aug 2026
  • quant-degradation-community — KLD delta vs bf16 @ Q6_K · aggregated · 2026-08-30

    Editorial derivation: Q6_K is near-lossless; carried from full band.

Coding 7/10
data checked Aug 2026
Tool calling / agentic 7/10
data checked Aug 2026
Instruction following 7/10
data checked Aug 2026

FP16 — full precision (fp16/bf16)

61GB weights · e.g. bf16 + KV: 768MB at 8K · 3GB at 32K · 12GB at 128K
Math & reasoning 8/10
data checked Aug 2026
Coding 7/10
data checked Aug 2026
Tool calling / agentic 7/10
data checked Aug 2026
Instruction following 7/10
data checked Aug 2026
Long context 6/10
data checked Aug 2026

§2 Known issues & what fixes them

ISSUE-01 severe Q2–Q3 · math, tool-calling

≤3-bit quantization hits this MoE's expert weights hard: arithmetic becomes unreliable and tool calls produce malformed arguments.

Fix
Move up a quant band [strong]

Q4_K_M (~19GB) is the sweet spot; if you only have ~13GB free, a smaller dense model at 4-bit usually beats this model at 3-bit.

Fix
Code interpreter / calculator tool [partial]

Offload math to a tool — works because tool calling recovers at 4-bit+, but at 3-bit the tool calls themselves get flaky.

Evidence · 2 sources · community-consensus
ISSUE-02 moderate Q2–Q3 / Q4–Q5 / Q6–Q8 / FP16 · creative-writing

Fast and smart, but its prose reads utilitarian — repetitive sentence rhythms and little voice.

No fix
No known fix — choose a different model

Model character, not a settings problem. Gemma 3 12B writes better in half the memory.

Evidence · 1 source · anecdotal
ISSUE-03 mild Q2–Q3 / Q4–Q5 / Q6–Q8 / FP16 · instruction-following

Qwen3 models fall into endless repetition loops under greedy decoding — the model card itself warns 'DO NOT use greedy decoding'. Quantized builds hit it more often.

Fix
Prompt technique [strong]

Use the card's sampler settings (temp 0.6 / top_p 0.95 / top_k 20 in thinking mode; 0.7 / 0.8 / 20 non-thinking) and presence_penalty up to 1.5 if loops persist.

Evidence · 2 sources · community-consensus