Why do modern motherboards have so few PCIE slots?

PCIe Bifurcation pci e slot PCI-e 1x slot That's fine, but how do I relate these outputs to deduce what PCI type and version are the free slots in my server? I pcie 4 slot A PCIe or PCI express slot is the point of connection between your PC's “peripheral components” and the motherboard The term “PCIe card” and “

pcie slot dimensions Using lspci -vvv I can get the PCIE slot numbers of these 4 cards But how to match the PCIE slot number with the device name? For example one