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Message: <blockquote data-quote="drothgery" data-source="post: 4660978" data-attributes="member: 360">Almost all x86 CPUs now -- and most x86 server CPUs for a long time (way back in the Pentium II Xeon days) -- have supported 36-bit memory addressing via 'PAE'. That gets you a 64 GB address space. And in fact, PAE support is enabled by default in all modern versions of Windows, because it's also used for some security features (incidentally, current desktop 64-bit CPUs, even when running in 64-bit mode, really only allow a 40 - 48 bit physical address space, because, well, 1 - 256 TB of physical memory is probably plenty...).So why can't you access all 4GB of physical memory and your video card that way? Well, a great many 32-bit drivers don't behave well if they're trying to deal with addresss above 4GB. So Microsoft only supports >4GB of memory in really expensive enterprise server versions of 32-bit Windows that ship with dedicated hardware. However, this is something of moot point in the long run, because Windows Server 2008 is the last server version of Windows that will have 32-bit versions; Windows Server 2008 R2 (the server companion to Windows 7) is 64-bit only.</blockquote>