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I've taken this directly from system information:

  • Installed Physical Memory (RAM) 4.00 GB
  • Total Physical Memory 2.00 GB
  • Available Physical Memory 434 MB
  • Total Virtual Memory 5.10 GB
  • Available Virtual Memory 1.19 GB
  • Page File Space 3.11 GB

Also the BIOS reports a full 4GB available.

Note the 4gb installed, yet 2gb total. I understand that on a 32 bit operating system, you'll never get the full 4gb of ram, however typically you'll get in the range of 2.5-3.2gb of ram.

I have only 2gb available! My swap file goes nuts when I do anything! Note that I have dual SLI nvidia video cards, each with 512mb of on board ram, though I have the SLI feature turned off.

Anybody know why Windows might claim that I have exactly 2gb of ram total?

Note: previously asked on serverfault, but closed as "belongs on superuser" before this site opened: http://serverfault.com/questions/39603/windows-7-using-exactly-half-the-installed-memory (I still need an answer!)

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Out of interest to confirm a theory could you post your MB model as well as how much Memory windows reports on each Graphics Card. –  Diago Aug 18 '09 at 9:52
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6 Answers

up vote 13 down vote accepted

First of you will lose very much of your available memory with two graphic cards, that's 1GB of RAM lost right there plus the other devices.

There is a switch you can check in msconfig. Go to start, type msconfig and hit enter. Go to the boot tab, click advanced options. Check if the Max Memory option is enabled, if it is then disable it and reboot.

Edit:

The issue is with something called address space. On a 32-bit system you have 4GB of address space and all devices you need to use have to be mapped into the address space. Each device that gets mapped in will carve out a bit of the address space and render it unusable for the rest of the system.

The only way to get more than 2.5-3GB of usable memory in Windows is to install the 64-bit version. After that is installed it will look the same with only 2GB of memory usable. To get all available memory you need to go into BIOS and enable an option called memory remap.

The memory remap features moves all the mapped devices above the 4GB limit in the address space thus freeing up your address space for use by the system.

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But the video cards have their own RAM; why would they need to steal it from the system? –  Nathan Ridley Aug 18 '09 at 9:51
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They have their own RAM, the issue is with something called address space. On a 32-bit system you have 4GB of address space and all devices you need to use have to be mapped into the address space. Each device that gets mapped in will carve out a bit of the address space and render it unusable for the rest of the system. –  Pär Björklund Aug 18 '09 at 9:55
    
Ah..! Interesting. Perhaps I should install 64 bit Windows? –  Nathan Ridley Aug 18 '09 at 10:04
    
yup, it's the only way to use more than 2.5-3GB of memory –  Pär Björklund Aug 18 '09 at 10:05
    
Note the Max Memory option was turned off already. –  Nathan Ridley Aug 18 '09 at 10:05
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I too had half memory, I built one with Windows7, Asus P7P55D-E motherboard and 4GB memory. I tried to add 4GB more and it locked up. Thats when I saw it was cutting memory in half. I swapped first 4GB with Second and made sure mapping was eabled and this solved the problem.

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Have you tried DISABLING memory remapping in the BIOS? Because on AMD64 systems with IMC, one common method of memory remapping (hoisting) can leave you with only 2GB below the 4GB line, and it was the only method available prior to Revision E K8 processors.

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I am running the 64 bit version with 6 gb of mem and getting the 3gb usable message- the max memory option is turned of and the bios sees the 6gb. I have one video card with a 1gb of mem on board. SO installing the 64bit is not the answer- there is something happening here that ms needs to address

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You really ought to use a 64-bit OS.

Dude, Where's My 4 Gigabytes of RAM?

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Yeah I'm aware of the addressing thing; the thing that threw me was the fact that I'm on less than the normal 2.5-3gb ram one would expect and that the amount available is EXACTLY half the full amount. –  Nathan Ridley Aug 18 '09 at 10:07
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bottom line: it's not worth the brain damage. go 64-bit. There's almost no reason not to, these days. –  Jeff Atwood Aug 18 '09 at 11:07
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Thought I should follow up on this. I went 64 bit a month or so after posting this question and never looked back. Not one compatibility problem I was afraid of ever showed its head. I can't imagine why anyone would still go 32 bit anymore. –  Nathan Ridley Aug 19 '10 at 11:29
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Did you check if BIOS reports 4 GB installed? Maybe (one of) the memory chips are not inserted properly in the slot?

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Yes, the BIOS reports 4GB installed. –  Nathan Ridley Aug 18 '09 at 9:50
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