Instead of risers just use pcie ender cords and you can get 4x 3090's working with a creator motherboard (google one that you know can handle 4). You could also

Instead of risers just use pcie ender cords and you can get 4x 3090's working with a creator motherboard (google one that you know can handle 4). You could also use a mining case to do the same. But, the advantage is that you can load a much more complex model easily (24GB vs 32GB is much easier since 24GB is just barely around 70B parameters).