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Why does Windows only show about 3.5GB of my 4GB+ of RAM?

My system RAM is 4GB, but it shows 3.80GB RAM in system properties, Why is it so? Is this something related to 3GB barrier as I'm using a 32bit OS?

Regards Athreya

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migrated from Apr 7 '11 at 10:01

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marked as duplicate by Mokubai, Sathya Apr 7 '11 at 10:56

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Perhaps on-board video card is stealing 256 megs? Check BIOS at boot. – sarnold Apr 7 '11 at 9:54
up vote 2 down vote accepted

It's allocated as shared memory. Possibly, your graphics card uses that.

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I heard that depending on the type of memory used, it is not always possible to physically address the entire 4GB, you may found that you can only address up to 3.5GB, 3.8GB etc. This is a chipset limitation rather than BIOS or motherboard design.

Maybe check your motherboard/chipset manual.

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There are several possibilities.

  1. You may have a graphics card (or, less likely, some other peripheral device) which is taking up some of your system RAM for its own use.
  2. You're using a 32-bit OS that isn't configured to use PAE or PSE and is thus not able to make proper use of all your available RAM (for a variety of complicated reasons).

Solving this depends, of course, on which issue is at work here. Given that you're missing 256MB I'd guess it's the first, though, and the solution is to either adjust the amount of memory you give to your video card downward or to get a video card that doesn't suck up your system RAM.

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In a 32-bit operating system you only have access to 4GB of memory address space.

In that 4GB you have not only the RAM, but any shared Graphics memory, the IO address space, and any ROM space, like the BIOS, etc.

So your 3.8GB is perfectly reasonable - that leaves 256 meg for a sensible graphics card, plus a few extra bits around the place.

If you want the full 4GB of RAM then you would need to switch to a 64-bit operating system.

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