x570 Multi-GPU: Swap CUDA Order to Double Prompt Speed
On x570 boards with asymmetrical x16/x4 PCI-E lanes, default CUDA0 uses the slow x4 slot, bottlenecking prompt processing in llama.cpp. Setting export CUDA_VISIBLE_DEVICES="1,0" prioritizes the x16 GPU, doubling speed from 70 to 140 t/s for MoE models. Verify lanes with nvtop or lspci before applying.

