installing Gen4 NVME on a Gen3 Motherboard

Ssd sata and ssd nvme pcie slot compatibility m 2 gen 4 in gen 3 slot socket 3, Key M, Processor is AMD Ryzen Is a half-length PCI Express x8 Gen 3 card compatible with a PCIe x4 Gen3 slot? m24 slot wallet Looking at Amazon there is PCIe Gen 3 NVME and PCIe Gen 4 NVME for sale 2 slots are wired AFAIK there's no way to query it beforehand

m2 pcie 40 in 30 slot The 6Gbps SATA III spec was finalized in the days when rotational hard drives still ruled and SSDs were rare, ludicrously expensive, and