USB PCIe card in x16 slot?

A x8 card will work in an x1 slot, but will be limited to x1 speeds A x8 card will also work fine in a x4 slot It will be limited to x4 speeds

PCIe x16: This is the largest PCIe slot with 16 data lanes PCIe x16 slots are associated with graphics cards and provide the highest bandwidth

pcle x1 slot A x8 card will work in an x1 slot, but will be limited to x1 speeds A x8 card will also work fine in a x4 slot It will be limited to x4 speeds

pcle x16 slot GPUs are usually installed in the top x16 slot, as it has the most bandwidth and, traditionally, the most direct connection to the CPU Modern PCIe SSDs use