Plated PCB edge contacts used for expansion cards.

Device strengthening or conditioning PCIe signals.

Large PCB copper area used for power or ground.

Hot-air solder-leveling PCB surface finish.

Motherboard connector for an expansion card.

Splitting one PCIe slot into multiple lane groups.

Copper area connected to electrical ground.

Organic solderability preservative PCB finish.

Older expansion slot for peripheral cards.

Capability to add or remove PCIe devices while operating.