Since I’m not a big windows user, except for a desktop that his only purpose is to download Linux distros using bit torrent protocol, I was not fully aware of this limitation.

So I did some quick research and realized that this limitation was not a Windows problem, but a hardware problem! You see, 32-bit systems have a limit of memory that they can use. Normally this is 4GB minus the total ammount of memory in the Video Card, the BIOS and everything inside you machine that has memory. So most of the users that now buy 4Gib ram to use with their brand new Vista machine, get stucked at 3 ou 3,5 Gib.

Even thouhg Linux also suffers from the same limitations, it is able to handle higher memory installed, since it uses correctly the PAE… What is PAE you might ask? PAE, or Physical Address Extension is a feature that allows the use of more than 4Gib of physical memory, given apropriate operating system support for this feature.

There are some things you might do to enable PAE in 32-bit Vista, but I haven’t tryed yet this.. maybe in the future…

Here are some places you can go, to read a little bit more and try for yourself:

• Enabling PAE in Vista
• Wiki on PAE
• Microsoft on PAE in Vista

In the future, this limitation will be overcome, since the use of 64-bit systems sets the memory limit much higher. If you want 4Gib, with no hassle just switch to a superior operating system like GNU/Linux or Mac OS X =)