AGP, Accelerated Graphics Port, is an interface introduced by Intel in 1996 as an answer to the increasing 3D requirements which could not be handled by the PCI Standards used at that time. Since its appearance, different versions of AGP were released in order to keep up with the race for performance.
History of Video Cards
At the time the first personal computers hit the market back in the 70s, their video capacities were totally ignored and totally useless but things changed quickly. With the evolution of PCs, the software also evolved, and in the early 1980s, the demand for more video power became obvious. The early systems, such as the ATARI 2600 had integrated video chips, but the demand for upgrade possibilities lead to the appearance of removable video cards. The ISA slots were used for video cards at first in 1984 when the 16 bit versions were released, followed by the PCI, and the increasing need of power led to the appearance of the AGP slot in 1996.
Evolution of AGP
The AGP was the first dedicated video slot. The ISA and PCI slots could be used for connecting multiple peripherals such as sound cards or LAN cards, whereas the AGP had only one use: video. The first version of AGP, 1x, delivered a speed of 266 Mb/s, boosting up to 533 Mb/s for the second. The third and fourth generations doubled up, delivering 1.07 GB/s for the AGP 4x and 2.14 GB/s for the AGP 8x.
Advantages of AGP
The best feature of AGP is the fact that it has direct access to the RAM and this greatly improves its speed compared to the PCI. Also, communication between the video card and CPU is faster, leading to better performance.
AGP 8X vs. AGP 4X
The 8X and 4X versions of the AGP are the most widely used. The slot on the motherboard itself is more important than the video card, as the motherboard slot will set the compatibility. AGP cards are backwards compatible, so a 8X card will work in a 4X mode too, and may be compatible with a motherboard fitted with a 4X slot, but will need a 8X slot on the motherboard to use its full power. Choosing a motherboard with an AGP 8X slot will assure compatibility and the best results with both 4X and 8X cards.
The main disadvantage of the AGP is that it cannot work with two or more video cards. As games and 3D applications evolved, the need of 3D rendering power exceeded the capabilities of the AGP. The PCI Express Standard was introduced in 2004 as an answer to the problem, being capable of using multiple video cards thus increasing performance.