What is a PCIE slot? Important slots on a Motherboard?

pci slotPCIe Slot Structure. All PCIe slots are divided into two parts by a small protrusion in the middle separating them. This is why PCIe expansion cards, such as graphics cards,A PCI slot is used to connect other processing cards to the main motherboard. Most motherboards use PCIe slots (PCI express). Motherboards