Knowledgebase
Windows and the 4GB Limit
My system says the maximum is 4GB, so I've installed it BUT not all 4GB are showing up in Windows. Is there something wrong with the memory or my machine?
There is nothing wrong with the memory or the machine itself - 32-bit operating systems have a limit of 4GB, but that also includes where attached devices (e.g. sound card, video card, Ethernet, modem, etc.) are stored within Windows. In other words, the better the system you have, such as a higher end video card with a large amount of memory on-board, the less memory you'll have access to from the 4GB.
There's a Microsoft support article talking about this in regards to Windows Vista.
There's also a good semi-technical article summing up the basics of what's going on behind the scenes, which should help give you a clear idea of the situation.
