What are the Differences between Gen4 and Gen3 PCIe SSDs?

PCIe Motherboard pcie 4 in pcie 3 slot ssd Yes, PCIe standards are thankfully backwards compatible, meaning that a PCIe device will work in a PCIe slot, but it will only be able to reach PCIe pcie 4 slot Does anyone know if you can buy a PCIe x16 low profile card that supports FOUR M2 NVMe drives? I found this Supermicro card which

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