Can I insert an SSD with PCI-Express x4 to a PCI-Express

There are some differences between PCI 3 vs PCI 4 compatibility Although both PCIe and PCIe are backward and forward compatible, those

4-3, per single PCI Segment Group show less , ECN, November 18, 2018 SMBus interface for SSD Socket 2 and Socket 3 SMBus interface signals are

pcie 4 in pcie 3 slot Max Bandwidth x16 Slot: 4 GBs , 4 GBs ; Notable for being the first generation of PCIe, introducing higher speeds than the previous PCI interface

pcie 4 gpu in pcie 3 slot Memory Slots 8 · 6 · 4 · 2 Graphics Interface PCIe · PCIe · PCIe PCIe x 16 Slots 7 · 6 · 5 · 4 · 3 · 2 · 1 SSD Slots 5 x · 4 x