Can I Run Qwen 3.8 27B Instruct on AMD Radeon RX 7900 XT (20GB GDDR6)?
Full VRAM footprint analysis, tokens/sec generation benchmark, and copy-paste Ollama & vLLM runtime commands for running Qwen 3.8 27B Instruct (27.2B) on AMD Radeon RX 7900 XT (20GB GDDR6) (20 GB).
⚠️ Partial Offload — Slow CPU/RAM Spillover
OLLAMA_FLASH_ATTENTION=1 OLLAMA_KV_CACHE_TYPE=q8_0 ollama run qwen3.8:27bLocal Hardware Configurations & Pricing
⚡ Partial Offload: Dedicated 100% GPU OptionsNVIDIA GeForce RTX 5090 (32GB GDDR7)
Maximum tokens/sec on 27B–35B models & Blackwell FP4 quantization
NVIDIA GeForce RTX 4090 (24GB GDDR6X)
The 24GB CUDA enthusiast standard for 14B–32B Q4_K_M models
2x NVIDIA RTX 3090 Dual Rig (48GB Total VRAM)
Best price-to-VRAM homelab rig for 70B Q4_K_M & Qwen 3.8 27B Q8
AMD Radeon RX 7900 XT (20GB GDDR6)
Sub-$700 GPU with 20GB VRAM fitting 14B Q8 and 27B Q4 models
⚠️ Out of VRAM? Don't downgrade model quality.
Out of VRAMSpin up an on-demand cloud GPU instance in 60 seconds with pre-installed Ollama and vLLM. (Qwen 3.8 27B Instruct @ 21.93 GB VRAM)
Quantization Precision Matrix
32K ctx • KV: Q8_0| Quantization | Weights | KV Cache | Total VRAM | Est. Speed | Fit Status |
|---|---|---|---|---|---|
| FP1616 bpw | 54.4 GB | 4.29 GB | 61.34 GB (307%) | 0 t/s | OOM |
| Q8_08.5 bpw | 28.83 GB | 4.29 GB | 34.88 GB (174%) | 0 t/s | OOM |
| Q6_K6.56 bpw | 22.3 GB | 4.29 GB | 28.12 GB (141%) | 0 t/s | OOM |
| Q5_K_M5.68 bpw | 19.31 GB | 4.29 GB | 25.03 GB (125%) | ~5 t/s | PARTIAL |
| Q4_K_M4.8 bpw | 16.32 GB | 4.29 GB | 21.93 GB (110%) | ~6 t/s | PARTIAL |
| FP44.25 bpw | 14.42 GB | 4.29 GB | 19.96 GB (100%) | ~30 t/s | FITS |
| IQ3_XS3.3 bpw | 11.15 GB | 4.29 GB | 16.58 GB (83%) | ~38 t/s | FITS |
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Frequently Asked Questions: Qwen 3.8 27B Instruct on AMD Radeon RX 7900 XT (20GB GDDR6)
How much VRAM does Qwen 3.8 27B Instruct need on AMD Radeon RX 7900 XT (20GB GDDR6)?
At standard 4-bit quantization (Q4_K_M) with 32K context, Qwen 3.8 27B Instruct requires 21.93 GB of total VRAM (weights + KV cache + CUDA runtime overhead).
What inference speed will Qwen 3.8 27B Instruct achieve on AMD Radeon RX 7900 XT (20GB GDDR6)?
Based on AMD Radeon RX 7900 XT (20GB GDDR6)'s 800 GB/s memory bandwidth, expected decode speed is approximately 6 tokens per second.
Can I expand context beyond 32K tokens?
Each additional 32K tokens of context requires additional KV cache memory. For longer context windows, consider 8-bit or 4-bit KV cache quantization.