Peripheral Component Interconnect, or PCI, slots are connectors on the motherboard of a computer that are used to attach different hardware parts. Becauswizard slotse these slots offer fast data connections between the motherboard and extra hardware, they make it possible to expand & customize the system and transfer large amounts of data efficiently. Standard PCI, PCI Express (PCIe), & mini-PCIe are the three sizes and configurations of PCI slots that are available.