Installed memory vs. Usable memory

  WaTcHiNg 13:57 23 Nov 09

I have an ASUS P5VD2-X motherboard with 4GB of RAM installed in 2 x 2GB DDR2 configuration.
When I boot up the BIOS tells me that I have 4096MB memory installed and 2495 usable memory.
If I take out individual sticks of RAM and install them in either socket the BIOS states installed 2048MB, usable 2047MB.

I understand that there may be times where video memory overlaps with the installed RAM and therefore reduces the amount available to the OS but my graphics card only has 512MB RAM. Worst I would therefore expect is to see 3.5GB usable. Where has the rest gone?

  xania 14:47 23 Nov 09

Hmmm. Your manual is not very helpful here. All I can find is a simple comment 'Due to chipset resource allocation, the system may detect less than 4 GB system memory when you install 2two 2Gb DDR2 memory modules'. I also know that, if you are working with XP Pro you will only be able to use some 3 GB of RAM in any case. You might like to post you query additionally with ASUS click here

  WaTcHiNg 14:52 23 Nov 09

I sent a request off to ASUS last week and still await their response - or even recognition that they received my request.

I'm aware of the XP and general 32 bit issue but I'm running Windows 7 64 bit hence why I'm gutted not to be able to take advantage of all 4GB now.

As I wrote earlier, the BIOS is detecting this reduced memory and so the OS has no chance of using more.

  xania 00:38 26 Nov 09

Take a look at your BIOS manual and check memory settings - there may be something there about using one or both channels with single/dual processors.

  WaTcHiNg 09:02 26 Nov 09

ASUS have just responded to my question saying:

My name is Chelesa and it's my pleasure to help you with your problem.

This model is to old, due to the chipset limitaion, you may don't have the option of memory remapping. Please try to uninstall any unnecessory devices, check if there more ram can be use.

Sorry for all the inconvenience and wish you have a nice day.

So, basically the board sold 2 years ago as 64 bit appears to have a limitation in accessing 4GB of RAM. Great! If I buy a new board I wonder if Microsoft will let me re-use my new Windows 7 key?

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