Question: I installed Windows XP x64 Edition on a system which is built by an Intel EM64T CPU and 4 GB memory on 775i915P-SATA2 / 775i65PE / 775V88+ / 775V88. Windows reports system memory about 3.0 - 3.5 GB. Why?(12/19/2005) Answer: Although the CPU and Operating system supports 64 bit addressing, Intel 915P, 865PE and VIA PT880 chipsets does not support remapping function. The missing memory addresses are reserved for PCI I/O space, AGP aperture mapping space, and other onboard device I/O space. Although the chipset datasheet may claim memory support up to 4 GB, the system actually only reports about 3.0 - 3.5 GB with four 1 GB DDR memory modules.