ASRock K7S8XE [21/27] Agp aperture size it refers to a section of the pci memory address range used for graphics memory it is recommended to leave this field at the default value unless the installed agp card s specifications requires other sizes usb controller use this to enable or disable the use of usb controller usb device legacy support use this to enable or disable the support to emulate legacy i o devices such as mouse keyboard etc dram cas latency this is used to adjust the means of memory accessing configuration options auto 2t 2 t 3t