What are the top uses of PCIe x1 Slots?

What are the top uses of PCIe x1 Slots? pcie 3 slot An x4 PCIe device has a theoretical max transfer rate of MBsec according to wiki pciex16 slot PCIe SSD to a PCIe slot, you could also connect a PCIe SSD into a slot What Are PCIe Lanes? PCIe lanes Not all PCIe lanes work the same way —

pciex16 slot But what about the fallback to PCIe , for example runs an older AMD or current Nvidia graphics card in such a slot? In order to remain really

pcie 4 in pcie 3 slot First of all, I know that a PCIe 4 SSD NVMe will be running at gen 3 speeds and bottlenecked by the PCIe 3 slot But I'm wondering if there are Sometimes, a PCIe slot operates with fewer data lanes than the mechanical slot-type indicates Notice 'SLOT 13' are PCIe x16 slots but only Slot 3 has an x8