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On my new laptop (Quad core i7, 8GB RAM, 250GB SSD, love it!) Windows 7 Pro 64-bit, I notice my daily memory usage is about 5GB. I used to run closer to 3GB with the same applications when on Windows XP Sp3 32-bit.

I understand that many of my applications are 32-bit still, and when shown in Task Manager, have a *32 next to their names. I also understand these run in WOW sessions. (Windows on Windows)

The question I have is, what is the memory overhead of that WOW session? When I add up the RAM usage in Task Manager, I come no where close to 5GB. Much closer to 3GB, and 2GB of lost RAM is moderately concerning to me.

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up vote 2 down vote accepted

Although not a direct answer to your WOW64 memory usage query, your 'lost RAM' in Windows 7 may be due to caching that you're not used to from using Windows XP. For example "SuperFetch".

Here's a good article explaining why it seems that Vista and 7 use so much more memory than XP.

Blurb: was little surprise that, upon checking my reported stats on XPnet, I found that I too was in the "alarming" position of having virtually no free memory. A quick glance at Task Manager revealed the truth. Though my "free" memory is indeed negligible, this is because so much is used by cache. The important number is not "free," but "available." The "available" memory includes both memory that is free, and memory that can be trivially made available, and this figure is far more representative of the true amount of memory available to applications. The vast majority of cached memory can be freed up near-instantly, since it is used up merely by cached data from disk.

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Good point on Free vs Available (+1 but not the answer I was looking for!). But I have been looking at the Available number. Currently running at 4GB Used, and 4GB Available. Only 343 MB free. – geoffc May 11 '11 at 17:24

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