Most CPUs have about 20 lanes (plus a link to the chipset).
On the one hand, they will be gen 4 or 5, so they're the equivalent of 40-80 gen 3 lanes.
On the other hand, you can only split them up if you have a motherboard that supports bifurcation. If you buy the wrong model, you're stuck dedicating the equivalent of 64 gen 3 lanes to a single card.
Edit: Actually, looking into it further, current Intel desktop processors will only run their lanes as 16(+4) or 8+8(+4). You can kind of make 4 cards work by using chipset-fed slots, but that sucks. You could also get a PCIe switch but those are very expensive. AMD will do 4+4+4+4(+4) on the right boards.
On the one hand, they will be gen 4 or 5, so they're the equivalent of 40-80 gen 3 lanes.
On the other hand, you can only split them up if you have a motherboard that supports bifurcation. If you buy the wrong model, you're stuck dedicating the equivalent of 64 gen 3 lanes to a single card.
Edit: Actually, looking into it further, current Intel desktop processors will only run their lanes as 16(+4) or 8+8(+4). You can kind of make 4 cards work by using chipset-fed slots, but that sucks. You could also get a PCIe switch but those are very expensive. AMD will do 4+4+4+4(+4) on the right boards.