How come my 2x2gb memory is only shown as 2.99gb in Windows XP.

An oft asked question. Hardware is taking up some memory. http://www.codinghorror.com/blog/archives/000811.html

No worries, you are most welcome.

Thats because the motherboard reserves a small bit for itself. Normally 640K(base) + 320K(high memory) meaning your total will always be 1 meg less than the amount installed.

Its XP, its s#!T, upgrade to Vista 64 Bit and use that extra memory! you will never go back

err, i wudnt know about that... 32ibit OS registers 4gb of mem as 3.25gb

it might be both actually, do you have vista or xp 32-bit? that could be taking away most of it

Wrong. XP sees only 4GB total, so it can be more or less than this amount. My XP sees only 2.75GB RAM for example. Typically, GFX cards eat around 512MB by themselves, sound cards can take 64MB, the motherboard takes 1MB. Throw in other parts (network card, SLI/CF, etc) and you can actually run out of system RAM (try it yourself, its a fun way to break windows ).

In theory, if you were to CF 2x 4870x2's, you could actually prevent Windows from booting, as all 4GB RAM would be allocated to the GFX cards...(has anyone tried this yet???)

^ Right on leokp, best and just about the only correct answer here. The rest of you, I don't know what in the hell you are all talking about.
I wish I had a dollar for everytime this question has been asked the last year.

WHAT?? The GPU memory and RAM on the motherboard are totally independent in this situation. Unless his GPU is onboard and uses partial system memory this will have nothing to do with it. You pay over $500 for 4870X2's because of the technology and the 2GB or GDDR5 Memory. Not the DDR2 that is probably in his motherboard. a 32bit OS usually can see 3gb of 4gb installed on the board in the RAM slots. I had 32bit XP before I got Vista x64 so I have actually seen it personally. In now way does a 4870X2 use 2GB of system memory. It has onboard memory.

Wrong. XP itself can only use 4GB. GFX RAM is nothing but RAM placed near the GFX card for storing textures, it behaves the same exact way otherwise.

As for the 4870x2, no answer for that one, although I can confirm 2x 9800GX2's start to eat into my system RAM under Vista (you can't run both on XP). In fact, it's possible ATI disabled one of the memory cores under XP, like NVIDIA did with 2x9800GX2's.

EDIT

The BIOS should always show the correct amount, and windows can be patched to "see" the proper amount, but 32-bit windows can only USE 4GB TOTAL RAM at any one point.

why do people bother with such an obsolete OS these days?

Wow, this forum just works perfectly. Continued:

Maybe it puts some of it into the I/O address space instead of the memory address space?