So I noticed all the new Ryzen boards X570 support PCI express 4.0
while I still have PCI express 3.0 on my Intel Z370 Coffee Lake.
I guess Comet lake will have PCI express 4.0 and maybe other…

PCI express 3.0 vs PCI express 4.0

Source: [H]ardOCP – PCI express 3.0 vs PCI express 4.0