XP Pro 64Bit only sees 3.54GB of 4GB RAM installed

Posted on 2007-07-28
Last Modified: 2013-11-10

I have a Desktop with XP Pro 64bit installed.  I have 4GB Corsair RAM on an ASUS A8N32-SLI Deluxe motherboard.  I also have 2 Geforce 7900 512MB graphics cards in SLI mode along with an Aegis PhysX PCI card.  For some reason I only see 3.54GB RAM in System Properties.  I've already turned on the memory hole option in the BIOS after reading on the Asus site and turned my virtual memory off.  How can I see the whole 4GB of RAM?

I've read in the forums regarding this issue and most of the topics refer to 32bit XP.  Almost every answer refers to upgrading to 64bit, but here I have it already installed and yet I don't see all of my RAM.


I look forward to whatever assistance anyone can provide.

Vic Wukovits
Question by:wukovits
    LVL 23

    Expert Comment

    by:Erik Bjers
    if there is an onboard video card, make sure it is disabled as these can use some of your system RAM

    If that is not the case down load memtest86 and test your memory

    THere is a good posibility you have a bad RAM module, take them out one at a time and boot your system, if you take one out and the total RAM does not go down, then that is the problem module.

    It can also be a bad MEM slot on the MOBO.'

    LVL 15

    Expert Comment

    This is standard.
    Do you have a /PAE switch in the boot.ini?

    Also here from Gene Caldwell

    "Phil, I have a similiar system and it flies. XP reports only 3.5 gigs ram. Depending on mother board this will vary from 3-3.5 gigs. XP will never report the full 4gigs due to hardware overhead. Your boot.ini file should look like this - [operating systems] multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect /userva=2800 /3gb /NoExecute=OptIn"
    (Only worry about the /fastdetect /userva=2800 /3gb /NoExecute=OptIn part)

    And here from ASUS
    (The one titled "4GB memory installed but less memory size detected")

    BUT you .5 gig not showing is seen alot. Windows is setting memory asides for hardware. This is also true for 64 bit without some boot up options in the boot.ini, but 64 bit will see memory PAST 64 bit alot easier than 32 bit.

    LVL 23

    Expert Comment

    by:Erik Bjers
    I don't agree with you qz8dsw, 2 of my XP systems have 4GB of ram and both see the full 4GB.


    Author Comment

    I'll give those webpages a good read and try a few of the suggestions and report back in.

    I would have thought XP 64bit was the solution to my RAM ailments, but sheesh, isn't anything ever easy?

    LVL 15

    Accepted Solution

    Windows is like that.

    I'm not saying you can't get to see the full 4 gig, it's just common more pronounced on 32 bit, but happens on 64 bit too. Depends on boot settings for windows and sometimes Advanced BIOS setting can have an impact and which way the wind blows.

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