What are the top uses of PCIe x1 Slots?

What are the top uses of PCIe x1 Slots? pcie 4 ssd in pcie 3 slot Best budget; 3 Best 2TB+; 4 Best for Steam Deck; 5 Best for PS5; 6 Best PCIe 5; 7 How to spot pcie x4 in x16 slot Solid-state drives offer more reliability and performance than traditional mechanical HDDs for greater uptime OCP slot with PCIe Gen 4 x16

pcie 4 m2 in pcie 3 slot PCIe 4 increases the PCIe generation's data transfer speed from 1GBs to 2GBs per lane, giving customers a total of 32GBs in a 16-lane