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I will be specific about everything, so I recommend reading the specs carefully and then replying with your ideal and logical answer.

The problem is: Windows 7 Ultimate 64bit's Resource Monitor shows 778 MB of RAM out of 4096 MB being hardware reserved. I am a user of virtual machines, thus I am in need of using even those 778MB. I am using a Pentium 4 3.0GHz 630 Prescott with motherboard's chipset Intel 945GZ Express which uses Intel GMA 950. As per the configurations given on Intel's website and listed on my system properties, I can come to a conclusion that the Intel GMA 950 which has a default 8 MB RAM is using my system RAM to increase itself to 256 MB. But the remaining 522 MB RAM's usage is confusing me. I cannot seem to find another hardware which might be consuming the remaining 522 MB RAM.

By googling I found some people saying that the chipset is the culprit, and the some saying that sound hardware also consumes RAM. Some people showed some tricks like deactivating the msconfig->boot->advanced->(uncheck) maximum memory. But these were not altered in my system. Some people say that an option for memory mapping in the BIOS will fix the problem, but my BIOS settings do not have any memory related settings.

Now what I am clear about is that if I add a graphic card with RAM=>256 to my system's only PCIe x16 V1 slot, then I can save 256MB RAM. But what about the remaining 522MB?

Please help me with this problem.

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possible duplicate of Why does Windows only show about 3.5GB of my 4GB+ of RAM? –  Mokubai Apr 23 '11 at 12:25
    
And also: Where did the other .8 GB of RAM go? and many others... –  Mokubai Apr 23 '11 at 12:27

2 Answers 2

Pretty much every piece of hardware in your system maps a portion of main memory to itself. Most devices won't take up any really noticeable amount, though.

You can see which device is using which areas (and therefore how much) of main memory by looking at the Device Manager snap in. Select "Resources By Connection" from the View menu and expand the "Memory" subtree. This will show all devices which are consuming memory along with the memory address ranges they're mapped to.

These ranges are in hexadecimal so unless you can read hex in your head you'll need some help in interpreting the data. You can use Wolfram Alpha for some quick conversion and calculation:

Say your video card is using memory range E0000000-EFFFFFFF Putting 0xE0000000-0xEFFFFFFFinto WA (note the ox added) and WA will give you -268435455 as the difference between the two. This is the number of bytes being used by the device. From there just convert into kilobytes or megabytes or gigabytes as needed (use KiB, MiB, and GiB respectively to get WA to convert into the binary form rather the decimal form): 268435455 bytes in MiB = 256MiB (Megabytes.)

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I tried your way Amazed and found that major memory usage was from these things PCI Bus & System Board. These two things had multiple existence and 1 of the PCI Bus existence was consuming around 530MB. I think that adding a Graphic card is the solution. –  Van Helsing Apr 23 '11 at 15:01
    
Was there anything listed under the PCI Bus with 530MB? –  Andrew Lambert Apr 23 '11 at 20:15
    
Hardware only maps address space to itself. It doesn't map any main memory to itself. –  David Schwartz Jul 13 '12 at 21:19
    
@David Schwartz true, but the address space is exhausted nonetheless. –  Andrew Lambert Jul 13 '12 at 23:42
    
@Amazed: It doesn't matter. A 64-bit CPU with a 64-bit OS has almost unlimited address space. –  David Schwartz Jul 14 '12 at 0:05

Click "Start" → type msconfig in the search box and press Enter. On the "Boot" tab, click "Advanced options" → make sure "Maximum memory" is not selected.

All memory is now available.

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