AMD creates the top X670E and X870E chipsets by joining two AMD “Promontory 21” FCH chips at the hip. Each of these takes in a PCI-Express 4.0 x4 connection, and puts out 8 PCIe 4.0 lanes and four SATA 6 Gbps ports that can be re-configured as four additional Gen 3 lanes. The X870E/X670E chipset hence has a total of 12 PCIe 4.0 lanes and up to eight SATA 6 Gbps ports on the platform. A company decided to put one of these chips on an add-on card, so you could upgrade your single-FCH platform, such as B650, B850, or X870, with more PCIe lanes wired out as additional M.2 slots, and some SATA ports.