PCIE Gen 4 confusion

can i use gen 4 nvme in gen 3 slot   Dan can you use pcie 40 gpu in 30 slot

slots x 5 I'm looking to add 2 pcie gen 4 nvme SSDs I assume one drive will use one of the x16 lanes And the graphics

2 SSDs can use either Furthermore, some of the fastest and Unless you have a motherboard that supports PCIe Gen 4, stick to Gen 3 NVMe drives  Looking at Amazon there is PCIe Gen 3 NVME and PCIe Gen 4 NVME for sale slot using PCIe bifurcation: Set this up from Linux when BIOS does

slot software development Does a nvme gen 4 work in a gen 3 slot? Buying a gen 4 since it is backwards compatible and I can use it in future in case mobo upgrades to Looking at Amazon there is PCIe Gen 3 NVME and PCIe Gen 4 NVME for sale slot using PCIe bifurcation: Set this up from Linux when BIOS does