I purchased a new, 500-MHz Celeron system for a very good price from a local computer shop, but it runs all my 3D graphics programs very slowly. I was told that the system supported DirectAGP. IÆd like to add a more powerful 4X AGP graphics card, but my PCÆs documentation doesnÆt specify whether the systemÆs DirectAGP is 2X or 4X. How can I find out?Peter WangChances are you canÆt. DirectAGP is a modified form of standard AGPùor Accelerated Graphics Portùtechnology that lower-cost systems use. Their graphics chips are usually attached directly to the motherboard, and they use the Universal Memory Architecture, which cuts costs by relying on the systemÆs main RAM instead of using its own RAM to process graphics. Unfortunately, these systems almost never come with an AGP port to accommodate an upgrade.

AGP moves complex texture data over a superfast connection between the graphics card and the PCÆs main memory; this frees the dedicated graphics memory to perform other 3D calculations. A PCI-based card can transfer graphics data at a top speed of 132 MBps, and it must share the PCI bus with other parts of the PC. A 1X AGP cardÆs dedicated channel moves data twice as fast (see FIGURE 3). Intel says architectural differences exclude DirectAGPÆs transfer rates from comparison.

You may be able to disable your on-board graphics chip and add a PCI-based graphics card, but the only way for you to realise the 3D performance of the latest graphics cards is to upgrade the motherboard (which may not even be possible) or to buy an entirely new PC.