官方網站查到的資料

AMD B550 Chipset :
1 x M.2_1 插槽 3, with M key, type 2242/2260/2280/22110 storage devices support(SATA & PCIe 4.0 x4 mode)
1 x M.2_2 插槽 3, with M key, type 2242/2260/2280/22110 storage devices support (SATA & PCIE 3.0 x 4 mode)*

擴充槽
AMD B550 Chipset
1 x PCIe 3.0 x16 (x4 mode) *
3 x PCIe 3.0 x1
1 x PCIe 4.0 x16 (x16 mode)

* Share bandwidth with PCIe3.0 x1_1, PCIe3.0 x1_2, PCIe3.0 x1_3
* When the M.2_2 Socket 3 is populated , SATA6G_5/6 ports will be disabled.