PCIe Gen 4 vs Gen 3 Slots, Speeds

The PCI Express interface doubles its connection speed for every new generation The current most popular PCIe slots are the PCIe Gen 3 with 1

As Zef said, PCI-e is backwards compatible You can put a PCI-e GPU into a slot or a PCI-e GPU into a slot, it'll just run

pcie slot x16 4-slot Customer Rating Top-Rated · 5 · 4 & Up · 3 & Up · 2 & Up PNY

pcie 2 slot I'd really like to have 1 PCIe x8 Gen 5 slot + 2 PCIe x8 Gen 4 slot + 3 PCIe x4 Gen 3 slots on such a backplane at the same time for instance