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Well, for that I have a board from Super Micro with Epyc in it.

NICs that can utilize x8 from PCIe 5.0 or even 4.0 probably don't usually go into consumer or even prosumer hardware. PCIe 3.0 x4 is enough for a single 10G NIC. One PCIe 4.0 x8 can handle 4 of those, double that on PCIe 5.0.

There is currently no GPU on a market with PCIe interface that can utilize PCIe 5.0 x8 fully.

Storage is probably the only area where what you get from PCIe is not enough. However, by the time such bandwidth makes sense - the price of CPU and motherboard is a drop in a bucket, and you are probably limited by more than just the number of PCIe lines.