Qwen3.8 27B
on 2× AMD RX 6800 XT 16GB · llama.cpp
Summary
User reports Qwen3.8 27B at 45 t/s generation and 450 t/s prompt processing on dual RX 6800 XT GPUs under Linux with ROCm.
Setup is llama.cpp with Q6_K weights and Q8_0 KV cache, using MTP speculative decoding and tensor parallelism across two gfx1030 cards.
User compares Windows 11 Vulkan results: 35 t/s TG and 180 t/s PP with MTP, 20 t/s TG and 360 t/s PP without MTP, and 15 t/s TG and 350 t/s PP with tensor parallelism and no MTP. User notes a Windows Vulkan bug that halves prompt processing and asks about performance ceilings and other engines.