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What happens when you install > 4GB of RAM in a computer with a 32-Bit OS?

I have 32 bit windows 7 operating System with 2GB RAM. One IDES Software has been installed in the system. But it runs very slowly. I have been told to increase the RAM to 6GB. But I have read that a 32bit operating system can use a maximum of 4GB RAM. I would like to know if this is true? If yes, how? What installing an extra 4 GB RAM improve the performance or do I have to change the OS to a 64 bit one?

marked as duplicate by Ƭᴇcʜιᴇ007, BBlake, Dave M, Supercereal, Indrek Sep 5 '12 at 13:09

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  • Who told you to increase the system memory to 6GB because its sounds like that person knows less then you do. A 32-bit operating system will not use more then 4GB, even if it it, increasing the amount of memory has never really made a computer faster. – Ramhound Sep 5 '12 at 12:31

You are correct. Unless you use a 64bit OS, the 32bit OS will not see more than 4GB Physical Memory Limits: Windows 7

The following table specifies the limits on physical memory for Windows 7.

Version              Limit on X86   Limit on X64
Windows 7 Ultimate        4 GB              192 GB

Windows 7 Enterprise      4 GB              192 GB

Windows 7 Professional    4 GB              192 GB

Windows 7 Home Premium    4 GB              16 GB

Windows 7 Home Basic      4 GB              8 GB

Windows 7 Starter         2 GB              N/A


However (and I appreciate this is probably not applicable to you, I include only for completeness), please note you can of course run 32-bit software on a 64-bit OS. The only way you'll get the full benefit is to run 64-bit software on a 64bit OS.

  • I have windows 7 Ultimate 32 bit. How can I know whether PAE is present in it or not? – Ashwin Sep 5 '12 at 13:01
  • It isn't. Not since XP service pack 2. The reason was that most drivers weren't PAE aware and threw their toys out of their pram if they ended up in memory above the 4 GB boundary. More details: superuser.com/questions/52275/… – Dave Sep 5 '12 at 13:03
  • What would be the result if it is a 32 bit processor but a 64 bit OS? – Ashwin Sep 5 '12 at 17:50
  • The software only utilises the 32 bit architecture and therefore only uses up to 4gb. However, depending on the code it is possible it won't run but unlikely. – Dave Sep 6 '12 at 5:48
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    This has been asked before so pleae search for a detailed answer but quickly, it is because the OS reserves X amount of memory. And it does vary between computers. – Dave Sep 7 '12 at 5:40

Per the TechNet article Memory Limits for Windows Releases, 32-bit versions of Windows 7 can support a maximum of 4GB of RAM. In my experience, even when I put 4GB of RAM in a 32-bit Windows 7 system, it only recognizes a portion of the memory (~3.6GB)


It depends largely on the OS. Most 'consumer' versions of Windows will be limited to 4GB on their 32-bit versions however the server versions have full PAE support (allowing up to 64GB)

Most Linux distributions will also allow use of higher amounts of RAM via PAE.

  • I don't know if this is the case - I think all (other than starter and possibly basic) W7 disc come with both 32bit and 64 bit discs. – Dave Sep 5 '12 at 11:36
  • Only when bought retail. If you've got an OEM installation then you may only have access to whatever version was originally installed. – PhonicUK Sep 5 '12 at 11:59
  • Ah, sorry. I now understand. Thank you for clarification. – Dave Sep 5 '12 at 11:59
  • @PhonicUK - You are mistaken. All Windows 7 licenses(except Starter and Basic) can be upgraded to a 64-bit installation. It is only Windows Server 2008 R2 that has specific licenses in that regard. Furthermore Windows 7 Starter and Windows 7 Basic cannot be "purchase" by a customer they are only found on specific devices meeting very specific guidelines. The right to upgrade to a 64-bit installation extends to an OEM license also. – Ramhound Sep 5 '12 at 12:34
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    +1, even though it might not be the best answer, I learned a new thing today: PAE. :D – user127350 Sep 5 '12 at 12:45

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