PCIe x8 NIC in PCIe x16 slot

Here's the best way I've found and seen of modifying a PCIE x1 slot to fit a full-sized x16 card

Any PCI Express card of a smaller size will fit into a larger slot So an x1 card will fit in an x8 slot Please see the Wikipedia article

pcie 4 m2 in pcie 3 slot PCIe x16 slots are generally intended for use with Graphics Cards PCIe 1x slots are generally for smaller add-in cards like Wifi Adapters, USB Adapters, or

pciex1 slot PCIe slots come in different sizes, with the most common being PCIe x1, PCIe x4, PCIe x8, and PCIe x16, which indicate the number of lanes