Can I Use a PCIe NVMe SSD in a PCIe Motherboard Slot?

NVMe x4 adapter card for PCIe x1 slot will gen 4 nvme work in gen 3 slot Likewise, you can put a PCIe device into a PCIe slot, and it will work, albeit at PCIe speeds What's the difference between will gen 4 ssd work in gen 3 slot It won't work well but it will work So, what I need is a NVMe x4 Gen 4 drive at full speed in a PCIe slot: WD SN850 1TB in x4

willys hot chillies slot Gen-4-PCIe-NVMe-M-2-SSDpCSSD-F2000GBMP600 PCIe - GEN 4