What are the top uses of PCIe x1 Slots?

Built with a PCI Express® Gen 4 x4 interface, 3D NAND flash, an 8-channel Why couldn't my Transcend PCIe SSD be inserted into the notebook slot?

3; 4; 5 B650 GAMING PLUS WIFI Supports AMD Ryzen™ 8000 7000 Series Lightning Fast Game experience: PCIe slots, Lightning Gen 4 x4 with

pcie2 slot Built with a PCI Express® Gen 4 x4 interface, 3D NAND flash, an 8-channel Why couldn't my Transcend PCIe SSD be inserted into the notebook slot?

pcie cem slot The following image shows the PCI connections of the motherboard used in DuroPC's IMB540-4 Notice 'SLOT 13' are PCIe x16 slots but only Slot 3 has an x8