I know my question today is subjective but I feel it requires some debate to once and for all put this myth to bed.

I've heard some myths and I'm not sure if it's true or false, but basically, the myth says that it's better to reinstall your Operating System if adding more RAM.

I know that Windows picks up the extra RAM and indicates that it does when just adding it without reinstall, but the myth (I've forgotten where I've heard/read it) states that even though Windows picks it up, it does not optimally use it.

Personally, I've added more RAM without reinstalling (Windows 7) and immediately found the System to be performing better, which in fact means that Windows did consume and is using the extra RAM (4GB).

Has anyone done any benchmarks?

I also don't know if benchmarks would help, because a reinstall of a OS would always outperform a long running OS because of the extra software that's inveriably installed when using a computer for a while.

Anyone have some thoughts on this?

  • 1
    I don't think the "myth" is about Windows 7. Is your question about whether there's a reason to reinstall Windows 7 after installing more RAM? Or is your question about whether it's ever advantageous to reinstall an operating system after adding RAM? May 10, 2012 at 8:28
  • 1
    The reinstallation thing sounds like one of those cargo cult ideas where somebody's computer crashed after installing memory and in their mind, they converted the need to recover from the crash to the need to reinstall Windows. Ensuing rumor and silliness follows. Sounds like something you'd find over on the Social.microsoft.com forums. Apr 27, 2013 at 20:01
  • I find that I need to reinstall the engine in my car every time I add gas to the tank. Could this be related?
    – fixer1234
    Jan 19, 2017 at 17:45
  • fixer1234 . funny, answer, but misguided. Adding RAM to your computer is not the same as adding gas to your car. Electricity in the pc might be the equivalent.
    – Fox
    Feb 12, 2017 at 20:24

5 Answers 5


Original answer (about reinstalling)

No, you don't need to reinstall your operating system. With Windows XP / Vista it is possible that you need to reactivate (my experience is that about 1 out of 10 XP/Vista needed reactivation after RAM upgrade), however this should go better with Windows 7.

Address space limitations (maximum usable memory)

However there is some limitations on how OS handles RAM. Most notable is difference between 32-bit and 64-bit systems, there if you have 32-bit Windows XP installed then you are limited to 4GB usable RAM even if you have added more than 4GB of RAM. If you need more than 4GB for programs then you must upgrade OS either to 64-bit or to one that fully [no hard limits] supports PAE.

See also:

  • Kingston Tech Support: How do I install memory into my computer?
  • wikipedia.org/wiki/Physical_Address_Extension
  • Hard memory limits for Microsoft Windows
  • Notes:

    • There's different versions of PAE (Physical Address Extension) supporting different sizes of virtual address spaces.
    • 32-bit Windows XP can not use virtual address expansions offered by PAE (see MSDN hard limits article).
    • Maximum address space and maximum program memory might be different (4GB/3,5GB for example).

    You need to upgrade to 64-bit if you install more than 4GB of RAM.

    Other than that you don't need to reinstall.

    Note that you'll need to reboot the machine cleanly afterwards. You won't be able to just "resume" from hibernate.


    No, OS reinstallation is not required after installing more RAM

    Reinstallation is preferred for major hardware changes to avoid conflicts due to driver issues, but barring a reactivation which may be required if you changed more that your RAM, nothing else is needed


    There are actually quite a few reasons why you might want to reinstall an operating system after adding RAM. However, if none of them apply to your situation, there's no reason to reinstall. For example, if you previously had 1GB of RAM on a Windows 7 system, you had to install the 32-bit version. If you upgraded to 8GB, you need the 64-bit version to use it all.


    There should be no reason to re-install Windows 7 after upgrading your RAM.

    You may have to reactivate Windows.

    It may also be worthwhile forcing a reassessment of your 'Windows Experience Index' under Control Panel - System. I don't know if it'd make a difference in your case but there is anecdotal evidence that such an action improves performance after an SSD is installed.

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