Expansion Cards for your Homebuilt Computer
Expansion cards are devices that extend a computer's capabilities and are inserted into expansion interfaces (or "slots") on the motherboard. Once upon a time, practically everything had to be installed into the motherboard as an expansion card. But early on in the history of the PC, manufacturers started adding more and more integrated peripherals right onto the boards; and nowadays, it's possible to buy a board that has everything everything the processor and the RAM built right in..
Depending on the motherboard you have purchased, however, you'll most likely need to install one or more expansion cards in your homebuilt computer. Many new motherboards have audio, video, and network "cards" built right into them. But if not (or if you don't want to use the integrated cards), then you will need to install expansion cards.
Types of Expansion Cards
There are many different types of expansion cards. The most common of these are:
Video cards, which provide a computer's visual output to a monitor or other video device. Some video cards also allow input from a video camera, VCR, DVD player, or other video sources.
Sound cards, which provide a computer's audio output to speakers or other audio devices. Most audio cards also allow sound input to the computer from a microphone or other audio sources.
Network cards and modems, which allow a computer to be connected (or "networked") to other computers on a local network, or to the Internet.
Controller cards, such as hard drive controllers. Although most motherboards have drive controllers built right onto them, controller cards can be purchased which allow the addition of newer or faster drives, RAID arrays, SATA drives, SCSI drives, and so forth to older motherboards that don't feature onboard controllers for these drive types.
I/O (input/output) cards, which can be used to replace a faulty onboard controller or to add more I/O interfaces (such as USB or Firewire interfaces) than were built into the motherboard. I/O cards are an inexpensive way to add a new type of interface to an older, but otherwise serviceable computer.
Expansion cards, fittingly enough, fit into expansion slots on the motherboard. It's important to purchase cards that correspond to the kind of slots your motherboard has available. You can learn to identify the different kinds of expansion slots by reading this page.