can i use pcie 3.0 ssd in 4.0 slot
Mainboard ASROCK B550M PRO4 (AMD B550, Socket ...
Up to 128GB Unbuffered ECC UDIMM, DDR4-3200MHz, in 4 DIMM slots; 1 PCIe 4.0 x8, 1 PCIe 4.0 x8 (in x16 slot), 1 PCIe 4.0 x4 (in x8 slot)1 PCIe 3.0 x2 (in x4 slot)
M.2 PCIe PCI-E Adapter, M.2 to PCI-E3.0 X1 Expansion Card,M2 SSD ...
Is it Possible to Install a PCIe 3.0 NVMe SSD in a PCIe 4.0 M.2 Motherboard Slot?
Question - PCIE 3.0 x8 into a PCIE 4.0 x4
That means a PCIe 4.0 Device in a PCIe 3.0 slot will work. However, it will be limited to operating at the max transfer rate of the PCIe 3.0 slot.