The size represents the number of direct connections provided by either a PCIe slot or card. While different sizes and configurations do exist, most users will only encounter four primary size specifications. The term “PCIe card” and “expansion card” simply refers to hardware, like graphics cards, CPUs, solid-state drives (SSDs), or HDDs, you may add to your device through PCIe slots, making both catch-all terms for a variety of components. PCIE SLOTS AND CARDSĪ PCIe or PCI express slot is the point of connection between your PC’s “peripheral components” and the motherboard. Manufacturers added “express” to distinguish the new standard from older PCI standards, emphasizing the substantial performance improvements over previous iterations. PCIe gets the “peripheral component interconnect” part of its name because it’s designed to handle point-to-point connections for non-core components.