The Accelerated Graphics Port (AGP) is used to install video cards in most of the computers manufactured from the late 1990s to the mid-2000s. Although Peripheral Component Interconnect (PCI) Express, a more recent standard, has become more popular, many AGP cards are still in production and are viable to use for upgrading an older computer.
Computer motherboard
Slot Location
On most motherboards, the AGP port is the expansion port closest to the processor (CPU). While the other expansion ports are generally red, the AGP port will usually be brown or maroon. Additionally, the port may have a plastic clip on one side, used to anchor the video card in place.
Identifying Card Types
AGP cards are identified by the power supply that they require from the motherboard, either 1.5 or 3.3 volts. Hold an AGP card up so that all of the ports are on the left side and look at the metal connectors on the bottom to determine an AGP card's type. The connectors will be notched in either one or two places. If the notch is on the left, the card requires 3.3 volts. If it is on the right, the card requires 1.5 volts. If there are two notches, it can support either standard.
Slot Types
AGP slots are keyed in the same manner as AGP cards to prevent the incorrect type of card from being inserted. AGP cards have slots in the metal connectors, and AGP slots have corresponding tabs. A tab on the left side indicates a 3.3 volt slot, and a tab on the right side indicates a 1.5 volt slot. No tab indicates that the slot can be used with either type of card.
AGP Pro
Some motherboards have AGP Pro slots, which are slightly longer than standard AGP slots. AGP Pro slots are able to supply more power to demanding high-end workstation graphics cards. Video cards requiring an AGP Pro slot are not common, but there is no need to worry if you have an AGP Pro slot in your motherboard; it will accept standard AGP cards. As with standard AGP slots, look for a tab on the left or right side to know the voltage the slot can deliver.
Warning
Although AGP cards are generally backward-compatible and will work in any slot that they fit into, the oldest motherboards with AGP connectors may be unable to supply the power necessary for newer AGP cards to function. Some motherboard chipsets to watch out for include the Intel 440LX and 440BX chipsets. Installing a recent AGP card in a very old motherboard may cause the system to become unstable while playing 3D games.
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