I have 3Gig of ram, but Windows only sees 2gig?

[Gibster]

Hi, im after some help from one of you computer wizzies.
I have 3 gig of DDR 400 memory in my pc (2 x 1g 2 x 512). I just installed a new motherboard and everything is running perfect except 1 thing:

Windows is only showing me as having 2 gig of ram instead of 3 gig, in both dxdiag and in system.
My Bios on the other hand, is showing the full 3 gig. It does not matter which way i put the memory sticks in, Windows XP is still only picking up 2 gig. This is not a visual error either as i notice the performance drop, nor are the sticks damaged as Bios is showing the full 3 gig.
May i also add - i just ran Everest and it also is showing 2 gig.
Also it showed 3 gig on windows before i switched motherboard.

Im really stuck here so if anyone knows why this may be happening, please let me know.

Thanks.

specs are as follow:

motherboard - ASUS A8N-VM CSM
chip - AMD 64 3500+
memory - 3 gig DDR400 (only showing 2 gig)
gfx card - Geforce 8800 GTX
Sound - Creative SoundBlaster Audigy 4
OS - Win XP SP2

 

[N3051M]

update driver for motherboard chipsets drivers
update windows with windows update service, and make sure you're running SP2

 

[LaNkY_mAtT]

i thought i heard somewhere that xp only shows 2 gig even when you have more

 

[Bluemouse]

I heard there was an issue with 64 bit processors/windows X64 and recognizing ram, though it may be only for >4GB

 

[rauckman]

I have the same situation but have 4 GB on board. I know there is a problem with >4GB being unmapable unless a couple changes are made in software o expand bits in memory address. I could not boot with a 512MB video card installed and had to drop to 256 on card or pull RAM so I could boot

 

[Mictlantecuhtli]

32-bit XP can't handle over 2 GB properly. There is a /3GB parameter you could add to boot.ini, but there's no guarantee it will help.

I haven't heard of any issues regarding 64-bit Windowses and CPUs - I've used 3 GB in XP x64 and Vista x64 without any problems.

 

[rauckman]

I have a link to a Microsoft page that explains it:

http://msdn2.microsoft.com/en-us/library/ms791558.aspx

If you have >256 mb on your video card, I think I would initially only boost it to 2.5 GB. I can tell you it is a pain when you exceed the limit and the machine won't boot until you put in a smaller video card.

It is strange that I did a Crucial memory scan tool examination and it suggested adding more RAM when I can't even use what I have,

 

[Mictlantecuhtli]

You could try a different AGP aperture size if you have an AGP card.