PCI Express x16 graphics card in a PCIe x16 slot?

Have you ever thought if you can plug PCI Express cards into x16 lane slot? In this video

slot is through the chips et while top slot where gpus go is directly from cpu GPU in x16 slot uses 16 PCIE lanes, NVME SSD (assuming a gen

pcie x1 slot function when you inserted the card in the top pcie 16 slot did it click in place? also what does the gpu info page in the bios say page 130 of the

pcie 4 in pcie 3 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