RTX 5080 and RTX 3090 Setup: 80 Tok/s on Qwen 3.6 27B Q8

A user successfully configured an RTX 5080 and RTX 3090 GPU setup to run Qwen 3.6 27B at 80 tokens per second by installing them on an Asus Prime X570-Pro motherboard and properly configuring BIOS settings to enable PCIe splitting and multi-GPU support. The setup required disabling CSM boot mode, enabling Above 4G Decoding and ReSize BAR Support, installing the appropriate NVIDIA drivers, and compiling llama.cpp with CUDA support for both GPU generations.