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Possible Duplicates:
Windows XP and RAM 3.5GB+
How to Check RAM Size without Looking at Motherboard

If Windows XP is a 32-bit operating system, and 2^32 equals 4GB, why can't it support 4GB of memory?

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marked as duplicate by ChrisF, Troggy, TheTXI Sep 30 '09 at 19:52

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.

Answer:… – Troggy Sep 30 '09 at 19:51
@Troggy - I missed that one ;) – ChrisF Sep 30 '09 at 19:53
I guess this question was closed due to loads of duplicates? Why are all the duplicates still open? – Chris Noe Oct 17 '09 at 12:21
up vote 2 down vote accepted

There are other types of memory that also need to be accessed, such as the video memory.

512mb is often used for your vram while the other 3.5 is used for your system ram.

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This is an in-depth discussion of the memory limitations of 32 bit technology and why you almost never see 4 GB of RAM in 32 bit systems. Written by a recognized expert in Windows systems, Mark Russinovich.

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32bit Windows can access up to 4, it's depends on your chipset you can sometimes access 3 and sometimes 4gb of ram

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There are many questions here that talk about that.

Here's a link to an answer with relevant links.

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