PCIe to 2 PCI & 2 PCIe Expansion System

4 x 8 lane PCIe cards; 8 x 4 lane PCIe cards (well you won't have enough PCI slots for that, as you need at least one for the Graphics

PCIe slots come in different sizes, denoted by their lane count The numbers x4, x8, and x16

pcie gen 4 in gen 3 slot PCIe compatibility and performance generates a LOT of confusion In Explaining PCIe Slots

pcie nvme slot PCIe x1: These are the smallest PCIe slots, used for almost any other cards like average network adapters and USB expansion cards · PCIe x4: