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I recently installed 8GB of RAM onto a quad core workstation (HP xw8600) running Windows XP Pro (32-bit). I added the /PAE switch in the boot.ini file, but the SysInfo is saying 3GB total memory still. Is Windows recognizing the extra memory? Is there a way to tell?

Any help is appreciated. Thanks.

quack quixote
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  • and you meant 8GB right...? – CookieOfFortune Apr 02 '09 at 20:32
  • How much will memory windows XP 64-bit recognize? – Roy Rico Apr 02 '09 at 20:33
  • 64-bit - 128 GB of RAM http://www.microsoft.com/windowsxp/using/64bit/russel_exploringx64.mspx – roman m Apr 02 '09 at 20:35
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    Here is a similar discussion about it. Please read my post: http://superuser.com/questions/67444/is-there-way-to-enable-4gb-ram-in-32-bit-windows-os/67596#67596 You can only use a MAX of 4GB in 32bit Windows, however, other 32bit OSes will be more than happy to use all 8GBs. It is a licensing thing with Microsoft. – Natalie Adams Nov 19 '09 at 15:01
  • If you don't want to reinstall your OS, you can consider using a RamDisk (PAE-enabled of course) to make use of that extra 4GB. – Suppressingfire Nov 19 '09 at 15:03
  • @quackquixote : What about [this](http://iknowu.dnsalias.com/files/public/Windows_XP_SP3_Remove_PAE_Limit/Windows_XP_Remove_PAE_Limit.htm "Windows XP SP3 - Remove the 4GB physical address / RAM limit and use up to 64GB RAM using PAE")? You can obtain usbport.sys by downloading windows server 2003 service pack 2. Then extract SP2.cab which is in the cab format... – user2284570 Apr 04 '14 at 20:25

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it's NOT about XP, it's about it being 32 bit ... 64 bit will support all your 8GB and then some

Windows XP Professional x64 Edition supports 128 GB of RAM

mirh
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roman m
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    not entirely true. PAE allows 32-bit OSs to access up to 64GB of RAM. The real issue is that MS deliberately doesn't use RAM found above the 4GB mark on 32-bit system due to common errors in 3rd party drivers. see http://blog.codef00.com/2007/12/19/windows-on-x86-and-4gb-of-ram/ – Evan Teran Apr 02 '09 at 21:17
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    In addition, my linux box (which is using a 32-bit kernel) currently happily uses 8GB of RAM through the use of PAE (the option is called enabled 64GB ram, but it basically means "turn on pae support" – Evan Teran Apr 02 '09 at 21:18
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from http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx

"Windows XP Professional and Windows Server 2003 Memory Support. The maximum amount of memory that can be supported on Windows XP Professional and Windows Server 2003 is also 4 GB. However, Windows Server 2003, Enterprise Edition supports 32 GB of physical RAM and Windows Server 2003, Datacenter Edition supports 64 GB of physical RAM using the PAE feature."

mirh
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John Boker
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    Why does the MS article say 4GB but everyone else is saying 3.x GB. It is confusing. – johnny Apr 02 '09 at 21:20
  • Finally someone gives a fully accurate answer! – Evan Teran Apr 02 '09 at 21:23
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    @jhonny: it is because that is 4GB minus any memory mapped devices ram (such as your video card). If you have a 512 meg video card, windows only acknowledges 3.5 of RAM (devices have to be mapped below 4GB for 32-bit DMA to work right). – Evan Teran Apr 02 '09 at 21:24
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XP will only recognize up to 3.5GB. So no, XP will not reognize the extra memory.

CookieOfFortune
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You can't have more than 3.5 GB on Windows XP Pro 32 bit edition.

robinCTS
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JP Richardson
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  • What about [this](http://iknowu.dnsalias.com/files/public/Windows_XP_SP3_Remove_PAE_Limit/Windows_XP_Remove_PAE_Limit.htm "Windows XP SP3 - Remove the 4GB physical address / RAM limit and use up to 64GB RAM using PAE")? – user2284570 Apr 05 '14 at 15:31
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This is totally off topic, but 32-bit Windows can't use more than 4 GB - desktop versions of Windows 32-bit will only give you about 3.5GB. (This limit is in place because buggy drivers often assume the top of the memory address space is not used and will crash your machine if you actually use up to 4GB. Servers are assumed to have better drivers.)

Neall
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    not true, if the OS supports PAE properly, it can use up to 64GB of RAM. Linux has been doing this for years. – Evan Teran Apr 02 '09 at 21:21
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32-bit operating systems max out around 3 gigs.

In order to take advantage of that much ram, you need a 64-bit os.

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    change that to "32-bit windows" and it's true. If the OS supports PAE properly, it can use up to 64GB of RAM. Linux has been doing this for years. – Evan Teran Apr 02 '09 at 21:22
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The short answer is no.

You can find the long answer here: http://blogs.technet.com/markrussinovich/archive/2008/07/21/3092070.aspx

mirh
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1

Switch to 64bit and you'll see the whole 8 GB.

Zaagmans
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  • What about [this](http://iknowu.dnsalias.com/files/public/Windows_XP_SP3_Remove_PAE_Limit/Windows_XP_Remove_PAE_Limit.htm "Windows XP SP3 - Remove the 4GB physical address / RAM limit and use up to 64GB RAM using PAE")? – user2284570 Apr 04 '14 at 20:28
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Here is a more detailed explanation, it's not about Windows, it's an x86 thing: http://www.codinghorror.com/blog/archives/000811.html

mirh
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MetaGuru
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    Actually unfortunately Jeff gets some pretty important details wrong. See this answer for the truth: http://stackoverflow.com/questions/711472/8gb-ram-on-xp-professional/711501#711501 – Evan Teran Apr 02 '09 at 21:27
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    My Linux box is happily using 8GB at the moment with a 32-bit kernel. – Evan Teran Apr 02 '09 at 21:28
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It seems like you're not allowed to use the PAE at all on a 'normal (non server)' 32-Bit Windows, maybe this does help (yes, I know it's for Vista...).

Bobby
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  • there's [this](http://iknowu.dnsalias.com/files/public/Windows_XP_SP3_Remove_PAE_Limit/Windows_XP_Remove_PAE_Limit.htm "Windows XP SP3 - Remove the 4GB physical address / RAM limit and use up to 64GB RAM using PAE"). – user2284570 Apr 04 '14 at 20:28
  • @user2284570 As far as I know, enabling PAE on a home system is a license violation. – Bobby Apr 05 '14 at 09:20
  • Yes and not only for home... For every non-server 32-bit windows version since XP SP2 (yes xp SP1 and windows 2000 support >4GB by manually adding the /PAE switch to boot.ini). – user2284570 Apr 05 '14 at 15:23