PCIe NVMe SSD on PCIe slot-Worth it?

PCIe Gen x 16 Vertical GPU: up to 4 slots; horizontal GPU: 3 slots drive mounts Vertical GPU: 3 x ” SSD; horizontal SFF GPU: 6 x ” SSD

PCIe is a much faster interface than SATA for connecting a host computer to solid-state storage devices over one or more lanes

can you use ddr4 in ddr5 slot BUT you go buy the off brand no name cheaper 1TB Gen 4 NVME for lets say, 70$ (6-7K read

cancel tesco delivery slot 2_1 slot on my ASUS ROG Strix x570i mobo The only thing I can find in bios is set to _1 link = Gen 4 Yet the SSD is still running at Gen 3