What are the top uses of PCIe x1 Slots?

PCIe NVMe SSD on PCIe slot-Worth it? using pcie 4 in 3 slot 2 slot is connected to CPU and supports the bandwidth of PCIe x4 The second and third slot can either choctaw slot machines 4-3, per single PCI Segment Group show less , ECN, November 18 with the link layer requirements in Chapter 3 of the PCI Express Base Specification

what slot machines win the most A single PCIe slot can now support x16, x8, x4, x2, or x1 lanes For example, PCIe x4 indicates a Gen 3 expansion slotcard with four lanes