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

I have recently purchased 8 GB of RAM to upgrade my system to go along with a new shiny i5!

When I run speed checks on my system online I get told I only have 3.5 GB of RAM, also in Task Manager I only see around that value of RAM yet that stupid Windows rating index tells me I have 8.0 GB.

Am I doing/reading/interpreting this incorrectly?

See below what I see:

Information about my system

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migrated from Oct 21 '11 at 16:55

This question came from our site for professional and enthusiast programmers.

marked as duplicate by shf301, Shinrai, Nifle, Kyle, bwDraco Oct 21 '11 at 17:26

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

One would think that this is common knowledge by now. – Daniel Beck Oct 21 '11 at 16:57

4 Answers 4

You have a 32-bit operating system. Because of this, your computer can only address 4 GB of the available RAM. That means, no matter how much you can stuff into your board (or how much your board can handle (as that could also be an issue)), your OS will only ever be able to work with 4 GB of it. The only real fix is to upgrade to a 64-bit operating system.

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And it's less than 4GB because of memory addresses for other hardware, primarily graphics card. – Daniel Beck Oct 21 '11 at 16:58

The clue is in the screenshot you provided. You're running a 32-bit OS which will only support 4 GB of RAM:

Enter image description here

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You have a 32-bit version of Windows, which can only use 4 GB maximum, because 2^32 is 4294967296. Some of that 4 GB is used for other purposes, so 3.5 GB is about the best you can do without a 64-bit OS.

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According to Microsoft, 32-bit versions of Windows 7 (which you are using) are limited to 4 GB of physical memory.

Memory limitations

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