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#11
Going to x64 does not guarantee that the OP will be able to see any more of that 4GB than the 32 bit OS would. In order to see all 4GB on x64, the computer's chipset must support at least 8GB of address space, and the chipset and system BIOS must support memory remapping. Without both of these the graphics memory will still use the upper 512MB+ of that 4GB of memory.
It is quite simple, the OS needs an address range to map the video memory and other device memory to so the system can read/write to the device using these addresses. This address range becomes unavailable for you to use as RAM. If your chipset only supports 4GB of RAM, it must map it the devices within that 4GB, so it is lost to you whether it is x64 or not. If your chipset supports 8GB or more, then the BIOS and chipset can map the devices to the upper part of the 8GB of address space *if* your BIOS has the memory remapping option which permits this to happen. In this case, if you have 4GB of RAM the full 4GB is available in X64 because the devices are mapped to addresses that are higher than that of the physical RAM.
- Gene
Last edited by GeneO; 29 Oct 2010 at 15:42.