Supermicro proprietary PCI-E slot adapter riser cards or cables?

The PCI Express slot commonly used for graphics cards is typically an x16 slot, which is one of the fastest connections on a motherboard

Depending on the motherboard you purchase, PCIe slots vary PCIe slots have a number of different physical configurations: x1, x4, x8, x16, x32

pcie slot function PCIe slots come in a variety of physically different sizes referred to by the maximum lane count they support, ie x1, x2, x4, x8, x16, and x32 A PCIe card

pcie2 slot PCI and PCIe slots PCIe: This slot comes in 7 versions: x1, x2, x4, x8, x12, x16 and x32, corresponding to 1248121632 lanes respectively