Windows XP 32-bit and the Missing RAM

09Aug07

I got my brand new screamer desktop at work. Core 2 Duo, 4GB RAM. Best machine I’ve ever had.

Then I went to run a server in Virtual PC, and noticed I didn’t have as much RAM as expected. Before I freaked out I hit Windows Key-Pause to check the amount of RAM Windows was reporting. To my horror I saw it was reporting 3.25GB! I ran down to the purchasing department (Kyle) and started ranting. Aren’t these computers supposed to have 4GB of RAM?! Dell is screwing us over!

Of course I opened the computer, and there were 4x 1GB sticks of RAM, so I checked the BIOS. 4x 1GB sticks of RAM.

A quick Google search (which is usually my first resource) revealed that even though 32-bit XP can address 4GB of memory, that addressing includes all your devices. So the video card is actually addressing that same 4GB memory space, even though it’s not actually accessing the system’s RAM. Windows figures out how much address space is required for all devices, then uses the rest of the memory address space for your system’s RAM.

I’m half-tempted to upgrade to 64-bit. My laptop is still available, so I may do it since I do have a backup machine available.

Reference: http://members.cox.net/slatteryt/RAM.html

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