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only 3gb/4gb RAM usable after Win 7x64 reinstall

Anonymous
2009-12-02T01:52:27+00:00

I know this is a common problem, but mine only started after a reinstall of windows so I know it's a change of settings and no hardware/motherboard/chipset problems. 

So after reinstalling windows 1025 mb of RAM is set aside for hardware but it WASN'T before (I am 100% sure of this). 800-900mb is always in use (for the OS and background processes presumably) on top of the 1025mb Hardware reserved RAM - this is the reading from resource monitor. The windows "system information screen" also confirms that 4gb of ram is detected, but only 3gb usable. 

To rule out ALL of the possible solutions I've seen on other threads:

  1. I am running 64 bit windows 7 NOT 32 bit.
  2. The unusable 1gb RAM is not being used by the OS, it's hardware reserved
  3. The video card, Nvidia GT 130m 1gb, shouldn't need that RAM - it certainly didn't on the factory install of windows
  4. I have tried disabling and enabling msconfig - boot - Max memory settings, neither option fixes the problem.
  5. There are no memory options in the BIOS settings to disable memory caching / memory shadowing.

EDIT: This problem actually may have presented itself in VISTA before I upgraded to Win7. The factory OS was Vista, which i reinstalled once before upgrading to Win7 - so that may be when it happened. 

I'm despairing, I've always tried to solve my problems on my own but I just don't know how to free up that 1gb of RAM again.

I did a scan using a program for these specs, so they're accurate and not just reading from the manual or something:

Asus n70sv notebook

System Specs:

Windows 7 (64 bit Home premium)

Processor:

2.67 gigahertz Intel Core2 Duo

64 kilobyte primary memory cache

6144 kilobyte secondary memory cache

64-bit ready

Multi-core (2 total)

Not hyper-threaded

Board: ASUS CORPORATION N70SV 1.0

Bus Clock: 267 megahertz

Updated BIOS (206 - 5/8/2009)

Video card Nvidia GT 130m 1gb

3072 Megabytes Usable Installed Memory

Slot 'DIMM0' has 2048 MB

Slot 'DIMM1' has 2048 MB

THANKS in advance for your help--!

Windows for home | Previous Windows versions | Devices and drivers

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  1. Anonymous
    2009-12-02T14:10:48+00:00

    That seems consistent with what I was just reading at Microsoft at

    This behavior is due to "memory mapped IO reservations". Those reservations overlay the physical address space and mask out those physical addresses so that they cannot be used for working memory. This is independent of the OS running on the machine.

    Significant chunks of address space below 4GB (the highest address accessible via 32-bit) get reserved for use by system hardware:

    • BIOS – including ACPI and legacy video support

    • PCI bus including bridges etc.

    • PCI Express support will reserve at least 256MB, up to 768MB depending on graphics card installed memory

    What this means is a typical system may see between ~256MB and 1GB of address space below 4GB reserved for hardware use that the OS cannot access. Intel chipset specs are pretty good at explaining what address ranges gets reserved by default and in some cases call out that 1.5GB is always reserved and thus inaccessible to Windows.

    I'm going to mark this as solved, but I have one final question: 

    If I had 3GB RAM, would it still have that 1GB reserved for the system leaving 2GB usable?  Is that 4th GB RAM helping my system at all while I play games?

    THANKS a bunch Dominic, I'll just bite the bullet and .. hope for a BIOS update in the distant future.

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  1. Anonymous
    2009-12-22T18:48:52+00:00

    Hello.

    I have the same problem Windows 7 Ultimate 64 bits 4GB and 3GB usable (1026MB hardware reserved memory)!!!

    Bios say 640KB (System), 4095 (RAM), 128MB (Graphic)!

    I tested my notebook with 2GB and the hardware reserved memory is 2MB!

    I tested my notebook with 3GB and still hardware reserved memory 2MB!!

    With 4GB hardware reserved memory is 1GB!??

    That is no answer, someone some how should make an update (motherbord, graphic board, windows 7) to realy do something to thousands of specialy notebook two years old other just a few months that without an explanation (yet) keep so much memory for nothing!!

    On new notebooks with windows 7 64 bits (they come all only 64 bits os) the hardware reserved memory is only 2GB - 4GB!!

    I think it´s time to do something.

    Thanks.

    Merry Christmas.

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  2. Anonymous
    2009-12-02T11:55:01+00:00

    PAE would need to be supported by the CPU and, again, enabled in the BIOS.

    There was considerable confusion with people upgrading from 32-bit to 64-bit and I believe at one stage Microsoft chose to avoid the problem by simply reporting the memory fitted rather than answering questions about why 4GB was installed but less was reported as available.

    There is another definition of "available": the free RAM currently available for programs. This is the RAM fitted less that in use by Windows and programs. This will vary according

    to your current activities and is more useful than any statement of hardware fitted.

    Look carefully at Resource Monitor: is the Hardware Reserved memory actually shown in the colour coded map? Mine shows 3GB of Hardware Reserved memory but none of that is mapped to the fitted memory. In Use, Modified, Standby and Free total to the 8GB fitted.

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  3. Anonymous
    2009-12-02T11:18:15+00:00

    Interesting Dominic.  

    I bought the computer refurbished and it came with Vista 64-bit; perhaps this wasn't the factory OS (i see no reason why they'd change it though) and at the time all 4gb were usable.  The reinstall of windows 7 is what changed it.

    What exactly does it mean to "report 4GB as fitted" and is there anyway I can duplicate the results on my current setup?

    My BIOS obviously doesn't support memory mapping/addressing options, and I've exhausted all upgrade options - none of the versions I've flashed have the options and I've decided to stop flashing (it doesn't seem like a good idea).  Why would the Asus n70sv ship with 4gb RAM that's unusable after system upgrade?

    So to "report the 4GB as fitted" I guess they had to change some hardware/driver/software settings.  Is there any way for me to do this myself?  I've read something about using a PAE parameter  on 32 bit systems at  http://support.microsoft.com/default.aspx/kb/291988 - would this have any effect on my 64 bit system?

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  4. Anonymous
    2009-12-02T07:56:24+00:00

    Vista 32-bit probably reported 4GB as fitted.

    With 64-bit, you can only gain memory address space over 32-bit if the hardware addresses can be mapped above 4GB. This is a setting which needs to be changed in the BIOS. However, as far as I can tell the Asus n70sv was only shipped with 32-bit Vista so it is unlikely that the setting is available in the BIOS. Look for it, but I doubt it is present.

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