Expansion cards

The expansion card (also expansion board, adapter card or accessory card) in computing is a printed circuit board that can be inserted into an expansion slot of a computer motherboard or backplane to add functionality to a computer system via the expansion bus.

One edge of the expansion card holds the contacts (the edge connector) that fit exactly into the slot. They establish the electrical contact between the electronics (mostly integrated circuits) on the card and on the motherboard.

Connectors mounted on the bracket allow the connection of external devices to the card. Depending on the form factor of the motherboard and case, around one to seven expansion cards can be added to a computer system. 19 or more expansion cards can be installed in backplane systems. There are also other factors involved in expansion card capacity. For example, most graphics cards on the market as of 2010 are dual slot graphics cards, using the second slot as a place to put an active heat sink with a fan.

Some cards are "low-profile" cards, meaning that they are shorter than standard cards and will fit in a lower height computer chassis. (There is a "low profile PCI card" standard[1] that specifies a much smaller bracket and board area). The group of expansion cards that are used for external connectivity, such as network, SAN or modem cards, are commonly referred to as input/output cards (or I/O cards).

The primary purpose of an expansion card is to provide or expand on features not offered by the motherboard.


Alternatively referred to as an add-on card, internal card, interface adapter, or just card. An expansion card is an electronic board or card added into the expansion slot of a desktop computer or other non-portable computer to give that computer a new ability, such as the ability to connect to another computer using a network cable.


Types of expansion cards in a computer

• Interface card (ATA, Bluetooth, EIDE, Firewire, IDE, Parallel, RAID, SCSI, Serial, and USB)
• Modem
• MPEG Decoder
• Network Card
• Sound Card
• Video Card
• Video capture card

An image of network card -

An image of TV tuner card -