What Does PCIe x16 Mean?

PCIe x16 Gen2 Host - PCIe Cable Adapter pcie 2 0 x16 slot There are 2 PCIe x16 slots on the T7400 Motherboard So if you only have the Graphics card in 1 of those slots then the other should be free pcie cem slot NVIDIA NVS 510 graphics board, Full Height Bracket , Low Profile Bracket , Four locking m-DP to DP Adapters, Four locking m-DP

pcie nvme slot but since im using the first pci-express x16 slot with graphic card i can only use the second slot and second pci-express x16 slot conforms