Why would a PCIe x16 slot be limited to PCIe x1 card?

GPU on PCIE 1x possible? 1 x pcie 4 0 x16 slot Includes a 200mm long PCIe Gen4 riser cable The latest PCIe supports double the bandwidth of PCIe and remains backward compatible with a maximum 1 x pci express x16 slot In this complete guide, learn everything you need to know about PCIe motherboards, slots, speeds, expansion cards, and whether you

1 cent slot one PCIe x16 input one PCIe x8 electical x8 mechanical output one PCIe x4 electical x16 mechanical output one 2280 slot (