expansion cards fit into slots on the
pcie-slots
PCIe (Peripheral Component Interconnect Express) slots on a motherboard are used to connect various internal components, primarily expansion cards, to the motherboard.
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For most devices, the expansion card fits into a slot in the computer called a PCI slot. However, in the case of video cards and a few others, they may fit into other types of slots, like an AGP (Accelerated Graphics Port) slot or a slot.
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In some cases, the installation of expansion cards can be tool-free, as well, with levers or other mounting schemes that eliminate the need for screws to clamp a PCI or PCI Express card into the case's expansion slots.
PCI / PCI Express / PCI-X Expansion Slots
An expansion slot is a place in a computer where a circuit board or expansion card can be inserted to expand the computer's capabilities. The boards inserted into the expansion slots are called expansion boards, expansion cards, cards, add-ins, and add-ons.