Short for Accelerated Graphics Port, AGP is an advanced port designed for Video cards and 3D accelerators. Designed by Intel and introduced in August of 1997, AGP introduces a dedicated point-to-point channel that allows the graphics controller direct access the system memory. Below is an illustration of what the AGP slot may look like on your motherboard.

AGP slot

The AGP channel is 32-bits wide and runs at 66 MHz. This translates into a total bandwidth of 266 MBps, which is much greater than the PCI bandwidth of up to 133 MBps. AGP also supports two optional faster modes, with throughput of 533 MBps and 1.07 GBps. It also allows 3-D textures to be stored in main memory rather than video memory.

Each computer with AGP support will either have one AGP slot or on-board AGP video. If you needed more than one video card in the computer, you can have one AGP video card and one PCI video card or use a motherboard that supports SLI.

AGP is available in three different versions, the original AGP version mentioned above, AGP 2.0 that was introduced in May of 1998, and AGP 3.0 (AGP 8x) that was introduced in November of 2000. AGP 2.0 added 4x signaling and was capable of operating at 1.5V and AGP 3.0 was capable of double the transfer speeds.

Tip: Not all operating systems support AGP because of limited or no driver support. For example, Windows 95 did not incorporate AGP support. See the Windows versions page for information about Windows versions that support AGP.

Today, AGP is being replaced by PCI Express.

What is AGP Pro?

AGP Pro is an AGP interface extension specification for advanced workstations. This specification delivers additional power to video cards, includes an extended connector, thermal envelope, updated mechanical specifications, I/O bracket, and motherboard layout requirements.

Related pages

Also see: AGP Aperture, AIMM, Bus, Expansion slot, Motherboard terms, Video terms