What Does PCIe x16 Mean?

A PCIe x16 slot provides powerful graphics card support The motherboard offers three slots, one of which is a PCIe x4 slot

You can put anything smaller than the slot in just fine It's the PCI-e bracket screw that really holds things into place I'd get the newest

pcie slot gpu Next Generation Storage：1*PCIe x4 and 2*PCIe x4 Connectors EZ-Latch：PCIe x16 Slot & Connectors with Quick Release & Screwless Design

pcie 2 slot Pci express x16 vs x8 vs x4