[Dopher]

I reciently built a new PC with an ASUS P5N-D system board. I have 2 @ 2GB Corsair DDR2 XMS2 memory modules in it. XP Pro only sees 2.5GB. The BIOS sees each stick at 2GB, but not Windows.

Anyone care to share why that is? Thansk!!

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Hi there,

Welcome to Geeks to Go!

There are plenty of answers out on Google if you want to go looking, start searching here. XP is a 32-bit operating system, (unless you specifically have 64-bit), which has a RAM limit of 4GB. Windows "allocates" part of your RAM for other uses, hence only showing a smaller amount. This amount is usually around 3-3.25GB, but is obviously a bit lower in your case, as every computer is different.

Cheers

Troy

[Troy]

Hi there,

Welcome to Geeks to Go!

There are plenty of answers out on Google if you want to go looking, start searching here. XP is a 32-bit operating system, (unless you specifically have 64-bit), which has a RAM limit of 4GB. Windows "allocates" part of your RAM for other uses, hence only showing a smaller amount. This amount is usually around 3-3.25GB, but is obviously a bit lower in your case, as every computer is different.

Cheers

Troy

[fdriller9]

is it dual channel?....i know some mobo's (like mine) require you to skip a slot in order for dual channel to work properly, check your manual

Edited by fdriller9, 16 June 2008 - 06:49 PM.

[Dopher]

I believe it is dual channel and it is in the appropriate slots. The strange thing, to me, is the BIOS show 2GB per slot, so the system board recognizes 4GB, but Windows XP Pro 32bit only sees 2.5GB. I even rebuilt the box, cuz i had to anyway, and got the same thing.

[Troy]

The strange thing, to me, is the BIOS show 2GB per slot, so the system board recognizes 4GB, but Windows XP Pro 32bit only sees 2.5GB.

Hi again,

It's not strange once you've read my response and researched why it happens.

Dual Channel doesn't have anything to do with how much memory is installed in the first place.

Cheers

Troy

[spsanderson]

I have the same problem with x32 Bit win 7 I guess I'll be upgrading to x64 as you get up to it looks like 7TB capabilities

[SpywareDr]

Various devices in a typical computer require memory-mapped access space which must reside within the first 4 GB of address space.

For example, if you have a video card that has 512 MB of onboard memory, that memory must be mapped within the first 4 GB of address space. This reduces the total amount of system memory that is available to the operating system by 512 MB.

The amount of reduction in available system memory depends on all the devices that are installed in the computer. If a computer has many installed devices, the available memory can be reduced to less than 3 GB.

[diabillic]

If you cant install x64 Windows, you can add /PAE to your boot.ini entry.