Expansion Slots

Table of Contents

What is an Expansion Slot?

An expansion slot is a type of port or socket on a motherboard that allows additional expansion cards for extended functionality. The purpose of expansion slots is to give computers flexibility and allow for hardware upgrades such as new modems, sound cards, and video cards.

Types of Expansion Slots

PCI Express

The PCI (Peripheral Component Interconnect) Express is the top choice when it comes to expansion slots. The PCI Express communicates with the motherboard, and therefore with the microprocessor, very quickly and efficiently. PCI-Express slots are generally used to connect more advanced video cards.


This PCI is probably the most common slot found on PCs today. Some PCs have a mix of PCI and PCI Express slots. If you have a choice, always go for PCI Express. PCI expansion slots are used to connect all kinds of devices such as network cards, modems, sound cards, and old graphics cards.


The AGP (Accelerated Graphics Port) has been specially designed for graphics adapters. Even though some older computers may include the AGP slot, it has mostly been replaced by the PCI Express.


The oldest type of extension is ISA (Industry Standard Architecture).