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I am having an issue with my motherboard "appropriating" memory. I have 2x2GB installed (exactly the same chips, brand new). The bios shows 4096 total with 1152 appropriated leaving 2944. When I only have a single 2GB stick in, no memory is appropriated. If I put a 2GB and a 1GB for 3GB total 128MB is appropriated and available still shows as 2944.

I've been all over looking for answers. There are no memory remapping options in the bios. I found that if I change to use internal vga instead of PCI-EX then only 640MB is appropriated. I've tried changing all of the other settings to no avail.

What is going on? Why is this motherboard appropriating memory and how can I get it back?

Motherboard: Asus P5GC-MX/1333
CPU: Celeron E3400
Video card: nVidia 9600GT PCI-EX

I have the latest bios. I dont see any jumpers on the board.

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If you set Internal Graphics Mode Select to Disabled and Boot Graphic Adapter Priority to PCI Express/PCI do you get it all back? Also, you are running a 64-bit OS correct? –  drew010 Sep 18 '11 at 8:27
    
no i dont get any of it back. Only if I switch to integrated graphics instead of PCI-EX. Yes I have Win7 64 but that has nothign to do with it. –  DustinDavis Sep 18 '11 at 20:41

1 Answer 1

up vote 3 down vote accepted

From your motherboard specifications page:

*When installing total memory of 4GB capacity or more, Windows 32-bit operation system may only recognize less than 3GB. Hence, a total installed memory of less than 3GB is recommended.

This is due, as you have found, to your graphics card and other devices needing to be mapped into the 32-bit (4GiB) address space.

Generally this is only seen with a 32-bit operating system, but if the motherboard is particularly old and badly designed then it can happen with a 64-bit operating system as well.

See my answer to What limits a motherboard from supporting more memory?, as well as other questions such as Why does my sytem only uses 3.2GB of my 4GM RAM?

Basically the first thing to try is running a 64-bit OS, for example a Linux LiveCD such as Ubuntu, to see if that can see the full 4GiB. If it cannot then it is a motherboard issue. If the memory can be seen then you will need to reinstall your current Windows version with a 64-bit version to use the whole 4GiB.

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Windows 7 64 says I have 4GB installed 2.97 usable. –  DustinDavis Sep 18 '11 at 20:33
    
Then more than likely it is a motherboard problem, I've seen a couple of questions and answers suggesting that even with a 64-bit operating system the Intel 945G chipset (which your motherboard is based on) is one of the most problematic to get to work properly with more than 3GB of RAM. The best and easiest thing you can do is upgrade your motherboard I'm afraid. –  Mokubai Sep 18 '11 at 21:08
    
I'm already looking. What would you suggest? I'm looking for budget. Obviously i need to stay away from 945G. How about G31? –  DustinDavis Sep 18 '11 at 21:26
    
From what I can see the G31 chipset is also limited to 4GB so may have the same problem, the G35 chipset on the other hand claims to support 8GB so I would expect it to work properly. You can see compatible chipsets on the Intel site for your processor: ark.intel.com/products/42772/… and I would expect the G35 or better chipsets not to have this "feature". If you have any futher questions it may be worth stopping by the SU Chat Room –  Mokubai Sep 19 '11 at 16:47

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