written by: Chris Hoffman•edited by: Simon Hill•updated: 4/12/2011
There are many different motherboard expansion slot standards. This article covers some of the most common and explains their differences and uses.
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What are Motherboard Expansion Slots and What Are They For?
There are many different types of motherboard expansion slots, but they all have one thing in common: They allow you to plug expansion cards into your computer and increase its functionality. While motherboards often come with on-board sound, wired networking, and video, plugging in a dedicated expansion card will result in this card being used instead of the motherboard's built-in hardware and can increase your computer's gaming, video playback, or sound performance. Expansion cards can also provide new functionality, such as allowing your computer to capture TV signals or access a wireless network.
Read on for information about common expansion slot types and functionality.
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PCI Express (or PCIe) is the newest standard for expansion cards on personal computers. PCI Express is meant to replace older standards like PCI and AGP, mentioned below. PCIe provides significantly more bandwidth, allowing for higher performance video cards and network cards. Video cards in particular are the most common consumer use of these slots, since they need high bandwidth for maximum 3D gaming and graphics performance. PCI Express slots have different versions and numbers of lanes, explained here.
While PCI Express is meant to replace the AGP and PCI standards, many PCI cards are still being manufactured, particularly for expansion cards which do not need the increase in bandwidth provided.
PCI Express is now dominating however, and motherboards are being manufactured with fewer PCI slots and more PCIe slots.
PCI (Peripheral Component Interconnect) is not to be confused with PCI Express, which is meant to replace it. Unlike PCI Express, PCI is an older standard which provides less bandwidth for expansion cards. In spite of the fact that the standard was created in 1993, new motherboards still ship with PCI slots for compatibility purposes.
PCI cards are still very common for expansion cards that do not need high bandwidth, such as most sound cards, network cards, USB expansion cards for additional connections, and more. Since newer motherboards still tend to come with PCI slots for compatibility, PCI cards will function on most computers. In contrast, PCI Express cards will only function on newer computers. Manufacturers can release expansion cards which function with most computers if the cards are PCI.
The AGP (Accelerated Graphics Port) expansion slot standard was introduced when video cards needed more bandwidth for performance than was provided by PCI. As suggested by the title, AGP slots are used for video cards. However, AGP has been largely phased out in favour of the PCI Express expansion slot standard. Unlike AGP, PCI Express provides higher bandwidth for other types of expansion cards that could use it, such as some newer, high-performance sound and network cards.
These standards are designed to be used with portable computers such as laptops. ExpressCard is the successor to PC Card (also known as PCMCIA), and, like PCIe over PCI, has more bandwidth. Unlike PCI, these types of cards are hot-pluggable (which means you can plug them in while your laptop is running, without shutting it down first).