Converting PCI-e to Asus X570 E model
Converting PCI-e to Asus X570 E model
You're venturing into the realm of server motherboards. What's available for consumers doesn't cover this level. When it comes to supporting both Gen 3 and Gen 4 simultaneously, a board capable of handling Gen 4 can also manage Gen 3, so you're after a model with several x16 slots. I'm not aware of any consumer boards that offer multiple full x16 slots electrically.