FitLLM

Can I run Qwen 3.6 35B-A3B on an RTX 5080 (16GB)?

❌ No — Qwen 3.6 35B-A3B (Q4_K_M) needs 26.0 GB but the RTX 5080 has 16 GB

Computed with the open FitLLM engine — accurate per-layer KV-cache modeling, not a naive estimate. Updated 2026-06.

Memory breakdown (Q4_K_M, F16 KV, 33K context)

Model weights19.9 GB
KV cache0.6 GB
Runtime overhead + reserve5.5 GB
Total used26.0 / 16 GB
Short by10.0 GB

Max context that fits at Q4_K_M: does not fit.

Every quantization on the RTX 5080

Weight quantWeightsFits (KV F16)Used @32K
Q4_K_M19.9 GB❌ won't fit26.0 / 16.0 GB
Q5_K_M23.2 GB❌ won't fit29.7 / 16.0 GB
Q6_K26.7 GB❌ won't fit33.7 / 16.0 GB
Q8_034.6 GB❌ won't fit42.5 / 16.0 GB
FP1665.2 GB❌ won't fit76.7 / 16.0 GB

KV cache is F16 here (llama.cpp default). Drop it to Q8/Q4 (-ctk/-ctv) for more context.

▶ Open the interactive calculator (this exact setup)

Why most VRAM calculators get this wrong

Qwen 3.6 35B-A3B is a hybrid model: only 10 of its 40 layers use full attention — the rest are linear and keep no growing KV cache. Naive calculators count every layer at full context and badly over-estimate.

What fits on the RTX 5080 instead

same GPU Models that fit on the RTX 5080: Gemma 4 e2b, Gemma 4 e4b, Gemma 4 12b.

same model GPUs that run Qwen 3.6 35B-A3B: RTX 5090 (32GB).

Reproduce it

Qwen 3.6 35B-A3B = 35B (3B active, MoE), 40 layers. The RTX 5080 has 16GB / 960GB/s. Same math, open source: fitllm-engine. GGUF bpw from llama.cpp.

All numbers are computed by the open-source fitllm-engine (MIT) from official model config.json values — reproduce or audit them yourself. Estimates; real usage varies with runtime (llama.cpp / MLX / Ollama), driver and display. Found a mismatch? Report it. · FitLLM home