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I just installed 2 gb extra ram memory in my pc (going from 2 to 4 gb). However, it seems like windows vista doesn't use it:

enter image description here

In windows task manager it says I've got only 3 gb of physical memory. In the system settings it does recognize 4 gb. Is this something that I should fix (for better performance). If so, how could I fix this ?

I still don't know how to fix this. I hope this screenshot will help identify the problem: enter image description here

I've no clue how installed RAM is 4 GB, and total phsycal memory is 2.94 GB. Can anyone explain ?

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Are you using integrated graphics? How much RAM is allotted to it? – Karan Jul 15 '13 at 17:06
Assuming you are using a 32-bit version of Vista, this is a duplicate of this question:… – uSlackr Jul 15 '13 at 17:31
@uSlackr I think it is clear from the picture that I'm using 64-bit. – Kasper Jul 15 '13 at 17:44
@Karan I don't have integrated graphics. I have ati radeon 1900 XTX – Kasper Jul 15 '13 at 17:44
Use RAMMap and see what's using the 1GB of RAM. – Karan Jul 15 '13 at 17:46

Mark Russinovich's article is still the best explanation for all this that I've found:

He discusses the memory ranges takes by drivers, etc that limit what's available in 4GB systems.

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Doesn't seem to explain why Total Physical Memory shown in Task Manager is 1GB less than the Installed Memory shown in System Properties. – Karan Jul 16 '13 at 2:58

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