Qwen3.8 27B
on 2× AMD RX 7900 XT · llama.cpp · 8,192 ctx
Summary
User reports Qwen3.8-27B at 46.4 t/s generation and 43.1 t/s prompt processing on 2× RX 7900 XT (20 GB each).
Setup is llama.cpp with IQ4_XS, F16 KV cache, 8k context, MTP3 speculative decoding, Flash Attention, and ROCm 2.46.0. The 27B tests used roughly 700 input tokens and 1024 output tokens.
Two separate IQ4 copies reached 103.5 t/s combined with 16 concurrent requests. Flash Next UD-IQ4_XS (93.7 GB) ran at 8.6 t/s on one GPU and 5.5–6.5 t/s on two GPUs. User asks whether the x1 PCIe slot, CPU/RAM offloading, or backend settings are the bottleneck.