Best case for dual RTX 3090 (250W each) on Crosshair VIII Hero?

I'm building a local LLM workstation and would appreciate some advice from people already running 2×3090s. Current hardware: ASUS Crosshair VIII Hero (X570) One Gainward Phoenix RTX 3090 Looking for a second used 3090 (not necessarily the same model) Both GPUs will be power-limited to ~250W I'm tryi