What exactly does the spec “PCIe x16 slot ” mean?

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 x16 is your 16-lane PCI Express slot, or at least your largestlongest PCI Express slot It is the most high-bandwidth, high-performance expansion slot

pcie slot gpu Verilux® NVME Adapter PCIe x16 with Gel Pad, NVME or AHCI SSD to PCIE Adapter Card for Key M 2230, 2242, 2260, 2280 Size SSD, Support PCIe x4 x8

pcie x16 expansion slot When attached to a motherboard's PCIe x16 slot, a card such as the GeForce RTX 4080 can draw up to 75W from the + and +12V rails ( x 3A + 12V x