PCI Express 4 vs PCIe 3: Is there a performance improvement?

Can I Use a PCIe NVMe SSD in a PCIe Motherboard Slot? pci 4 in pci 3 slot 3 Slot x16 Gen4 PCI Express Backplane · One PCIe x16 Gen4 uplink slot · Two PCIe x8 Gen4 Add-On slots · PCIe Gen1, Gen2, Gen3 and Gen4 compliant pcie 4 ssd 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 gen 4 in gen 3 slot 3 x PCI 2 x PCI 1 x PCI mini-PCIE Yes LAN 10 Gigabit 5 13, Intel X299, 8 x DDR4 DDR4 4200+, 4 x PCIe x16 1 x , AMD 3