Qwen3.8 27B
on 2× AMD RX 9070 XT 16GB · llama.cpp
Summary
User reports Qwen3.8 27B at about 30-50 tok/s on an RX 9070 XT paired with an RTX 3080, with performance dropping noticeably at 64k versus 128k context.
Setup is llama.cpp with Q4_K_M weights and Q8 KV cache, layer split rather than tensor split, MTP enabled, one parallel slot and flash attention on. MTP roughly doubles speed; the other tweaks mainly save VRAM.
The user calls the pairing a bad choice for LLM work, citing the 9070 XT's lower memory bandwidth and weaker ROCm/Vulkan performance, and notes task manager shows only about 60% and 30% GPU usage on the two cards. Monitors must stay on the 9070 XT or performance collapses.