Qwen3.5 27B
on AMD RX 9070 XT 16GB · llama.cpp
Summary
User reports Qwen3.5 27B at IQ3_S prefill of 1049.13 t/s (pp512) on an RX 9070 XT with the Lemonade B1356 ROCm build, against 460.03 t/s on B1357.
Setup is llama.cpp with IQ3_S weights (9.72 GiB), q8_0 KV cache, flash attention on, 99 layers offloaded and 512 batch.
Prefill falls from 1049.13 to 460.03 t/s at pp512 between B1356 and B1357, and rebuilding llama.cpp over B1356 returns the slow result. No generation figures are given.