Introduced in September 2002, Intel's AGP 3.0 specification keeps the same 32-bit-wide bus while redoubling speed to 8X or 533MHz, supporting a data rate of 2.1GB/sec, and cutting the signaling voltage again, to 0.8V. Backward compatibility has been cut off at the AGP 4X (1.5V) level, which means AGP 8X slots cannot use older AGP 2X (3.3V) graphics adapters.

Other than increasing bandwidth, deleting AGP 1.0 support, and changing the pin arrangement, other changes are less notable, mostly relating to performance (e.g., fast-write flow control) or feature enhancements (along with unneeded AGP 2.0 feature deletions). While most of these slide under the radar, one intriguing aspect of AGP 3.0 is its optional support for multiple AGP devices.

The standard AGP 3.0 implementation, as seen in Intel's E7205 chipset, allows for only AGP 8X or 4X, 1.5V cards. But what's good for Intel's chipsets may not be good for its licensees, who accuse the CPU giant of accelerating obsolescence or trying to retire older hardware to the dump before the consumer base is ready. So the list of available implementations is quite a bit longer than originally anticipated.

In addition to standard AGP 3.0, for instance, there's the Universal 1.5V AGP 3.0 Motherboard configuration, which supports only 1.5V graphics cards but allows backward compatibility for AGP 1X and 2X as well as 4X and 8X speeds. Still more versatile is the Universal AGP 3.0 Motherboard design, which allows both 1.5V and 3.3V cards along with all four speed options. You'll also encounter "AGP 3.0-compatible" platforms, which meet the AGP 8X bandwidth and performance specifications, but may or may not adhere strictly to all AGP 3.0 requirements.

Since the physical interface is standard, this also brings up some compatibility issues, especially in concern to AGP 4x- or 8X-only motherboards. AGP graphics cards, with some notable exceptions, also adhere to the same AGP 1.0, 2.0, and 3.0 specifications, which means that an AGP 8X-compliant video card uses 1.5V and can run in either AGP 8X or 4X modes.

Conversely, Intel AGP 4X and 8X motherboards support only 1.5V graphics cards, and usually ship with a cardboard insert in the AGP slot warning that hardware damage could occur with a 3.3V adapter. AGP may have brought some level of standardization to computer graphics, but it's important to know each chipset's capabilities and support before slapping in that old Voodoo Banshee.

What Comes Next

By now, you're probably looking forward to AGP 16X. Actually, that won't happen: Intel says the parallel architecture of AGP 8X is the last of its kind, and will be replaced in 2004 by none other than PCI -- or rather, a new serial I/O technology called PCI Express.

Also known as 3GIO (for Intel's third-generation I/O solution), PCI Express is a high-speed, general-purpose interconnect, compatible with current PCI technology, that allows point-to-point data transfers at an estimated 4.2GB/sec. It's meant to be a unifying standard, consolidating a number of input/output architectures within a platform.