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

What exactly does the spec “PCIe x16 slot ” mean? pciex16 slot configuration Configurations 3 PCIe slots Slot 1: PCIe x16 , low-profile Slot 2: PCIe x16 , full-height Slot 3: PCIe x16 pciex16 slot PCIe Slots are backward compatible like most of the interfaces, which means that you can use any generation card on any generation slot But

pciex16 slot Ensure peak performance in all configurations Adopt direct-to-chip liquid EZ-Latch：PCIe x16 Slot with Quick Release Design; Fast Networks：GbE LAN

situs slot indo Sometimes, a PCIe slot operates with fewer data lanes than the mechanical slot-type indicates Notice 'SLOT 13' are PCIe x16 slots but only Slot 3 has an x8 * For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot * The PCIEX4