how to tell how many nvme drive slots a motherboard has?

NVME drive not working in second slot of Asrock B450 m2 nvme slot The adapter card I am looking at can be used in a X4, X8 or X16 PCIe slot and they say I will get up to 32Gbps when it is plugged into a PCIe m2 slot mainboard In this video I discuss the difference between an SSD and a NVME PCI-Ex4 SSD From how

m24 slot wallet PCI-Express Gen4x4 supported NVMe SSD Storage space View of the expansion slot with the M2 SSD inserted diagonally into the PS5 console