It is the most high-bandwidth, high-performance expansion slot. 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). The Riser from Dell™ fits into the PCI-E slot of your Dell System. [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. 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. PCIe x16 is your lane PCI Express slot, or at least your largest/longest PCI Express slot. PCIe x16 slots are associated with graphics cards (GPUs) and provide the highest bandwidth available. . Typically, x16 slots are used for graphics cards, providing the highest bandwidth and performance. 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. This. PCIe x This is the largest PCIe slot with 16 data lanes.