The AGP Aperture size is an available option configurable through the computer CMOS setup that is usually set to a default size of 64MB. AGP aperture size defines how much system memory (not memory on your video card) the AGP controller uses for texture maps. While it may be possible to increase the overall video performance by increasing this value, we recommend leaving the AGP aperture size at its default size. Increasing the default size will only allocate more of your system memory, which is not used unless the program or game is capable of using it. In addition, because this allocates more system memory you will also probably see an overall reduction in system performance.