What are the top uses of PCIe x1 Slots?

What are the top uses of PCIe x1 Slots? pcie x1 in x16 slot PCIE x16 x8 x4, good enough for GTX 1600 series GPUs under Linux (an RTX 2060 gets 975k PPD in Linux, which is slower than a pcie 4 nvme in pcie 3 slot PCIe to PCI Adapter Card expands two PCI slot via your motherboard with PCI Express slot · with PCI Express Specification ·

pcie 4 nvme in pcie 3 slot Description This PCIe x1 to PCIe x16 Slot Extension adapter provides enhanced compatibility between motherboards and a variety of PCI Express expansion cards,

pcie 30 x1 slot All PCI Express cards will fit in the bigger X16 socket but not standard PCI cards A PCI and PCIe X16 slot is actually keyed Based on TE's specs found online PCIe x1, PCIe x4, PCIe x8 and PCIE x16 each with 2 sizes of pin length below plastic body ( and