Qwen3 8B

User reports Qwen3-8B Q4_K_M at 98.8 t/s decode and 4245 t/s prefill (pp512) on an RX 9070 XT with llama.cpp's HIP backend. Setup is llama.cpp b10290 official HIP build on one RX 9070 XT 16 GB, Q4_K_M weights, all layers on the GPU, Windows 11, no speculative decoding. The issue reports a Vulkan backend fault on the same card: Qwen3-8B Q4_K_M drops to 21.0 t/s decode and 791 t/s at pp128 there, and models with hidden size 4096 or more run 4.7-6.7x slower than on HIP, while Qwen3-4B is normal at 183.0 t/s. Qwen3-14B Q4_K_M runs 54.3 t/s on HIP against 8.1 on Vulkan.