Kinda New to all this, couple of questions about how to set pcs and what models

Ill address all the questions here not spam the sub what would be a better set up, 1 pc with 2 3090s and a 5080, but that 3090s will have to run at x4 pci-e slots OR 1 pc with 5080, another pc with the 2 3090s and on x16 split into 2x8 main pc cant be headless the second pc will serve as well for mass storage and some servers (i have other lesser cards for it if all these gpus go to the main system) for coding, what model would you use for a single 3090? (and what would you use for 2 while im at it) ive seen a lot of answer, ive tried to use unsloth qwen 3.6 35b but i often run out of.