[HOST] › › Storage Accessories › Accessories. PCIe slots come in different physical configurations: x1, x4, x8, and x The number after x tells you how many lanes (how data travels to and. Typically, x16 slots are used for graphics cards, providing the highest bandwidth and performance. This. PCIe x16 is your lane PCI Express slot, or at least your largest/longest PCI Express slot. PCIe x This is the largest PCIe slot with 16 data lanes. . Other devices, like network cards or storage. Riser cards are used to extend a slot for a chip or card in a fully loaded computer. The Riser from Dell™ fits into the PCI-E slot of your Dell System. PCIe x16 slots are associated with graphics cards (GPUs) and provide the highest bandwidth available. It is the most high-bandwidth, high-performance expansion slot. Two types of PCIe slot on an Asus H81M-K motherboard Various slots on a computer motherboard, from top to bottom: PCI Express x4; PCI Express x16; PCI Express. It's a slot of x16 size (meaning it accepts cards of x1, x4 or x16) but electrically x4 (meaning any card in it runs at maximum x4 speed).