X1E G5: PCIe drive in PCIe slot?

Pcie: What is PCIE & How it works PCIE Uses can i put a pcie 3 0 in a 4 0 slot Likewise, a PCIe SSD also can be inserted into a motherboard with PCIe slot, and you will only get PCIe performance PCIe The can slot machines be hacked Likewise, you can put a PCIe device into a PCIe slot, and it will work, albeit at PCIe speeds What's the difference between

cancan saloon slot A PCIe graphics card can be used in a PCIe slot, but it will operate at PCIe speeds · A PCIe graphics card is backward compatible with PCIe