Feb 09

When buying a new PC, should you spend the extra cash to upgrade your RAM?  Here’s a rule-of-thumb for how much memory you need to run Windows Vista:

Windows Vista RAM

  • 2 GB is minimum
  • 3 GB if you can afford it
  • 4 GB is mostly wasted (on 32-bit Vista)

If a PC has 4 gigabytes (GB) of random-access memory (RAM) installed, Windows Vista will show significantly less than 4 GB available memory.  For example, the Vista “System Information” dialog box may report 3,120 megabytes (MB) of memory available on a PC that has 4,096 MB (4 GB) of memory installed.  Note this only applies to the 32-bit versions of Vista; the 64-bit versions of Vista can access up to 128 GB of RAM.

To see how much memory you have available in Windows Vista:

  • Double-click System in Control Panel, -or-
  • Click Start, right-click Computer, and then click Properties

The missing RAM on a 4 GB system is “stolen” by various devices that require memory-mapped I/O (MMIO).  Since a 32-bit operating system can only access 4 GB of address space, these devices are granted space starting from the 4 GB address and working backward.  Devices include:

  • BIOS, ACPI and legacy video support
  • PCI bus for hard disks, sound cards, LAN cards, etc.
  • PCI Express can consume 256-768 MB for the graphics card

So if a PC has 4 GB RAM installed, some of that 4 GB is used for MMIO.  The amount of missing RAM depends on the devices installed in the PC.  But because of driver compatibility issues, the 32-bit versions of Vista limit available memory to 3.12 GB.

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Article published on February 9, 2008




43 Responses to “Windows Vista: 3GB or 4GB RAM?”

  1. Windows Vista News Says:

    Windows Vista: 3GB or 4GB RAM?…

    Interesting point at http://www.devtopics.com...

  2. Windows Vista News » Windows Vista: 3GB or 4GB RAM? Says:

    […] post by Timm Related ArticlesNo related […]

  3. Najlepsze Programy, Recenzje, Informacje. » Blog Archive » Windows Vista: 3GB or 4GB RAM? Says:

    […] Original post by Timm […]

  4. Windows Vista: 3GB or 4GB RAM? Says:

    […] unknown wrote an interesting post today onHere’s a quick excerptIf a PC has 4 gigabytes (GB) of random-access memory (RAM) installed, Windows Vista will show significantly less than 4 GB available memory. For example, the Vista “System Information” dialog box may report 3120 megabytes (MB) of memory … […]

  5. arex Says:

    I’v been using Vista just fine with 2 GB. Buy 3GB or more when the prices come down. 🙂

  6. Joel Says:

    I bought a Vista machine late last year. Thankfully, I had a geek friend who told me not to bother with more than 3GB of RAM because Vista couldn’t handle more than that, so I only ordered 3GB. I always thought it was a little weird, so thanks for verifying for me!

  7. vistxp Says:

    I read somewhere that Vista SP1 will address this problem with 32-bit Vista systems being unable to recognize 4GB of RAM.

  8. Tom Says:

    Hi guys
    Got a Medion pc with quad core processor running 2GB RAM on Vista premium
    Would like to upgrade to 4GB but read that anything above 3GB is a waste
    The DIMMS currently in the machine are PC2-5300u-55-12E3 ( 2x1GB)
    I have four slots can I use two PC2-6400u DIMMS in the other two slots?

  9. Mads Says:

    I just installed additional 4 GB RAM in my Win Vista machine (32-bit Home Premium) and with the 2 GB it already had, it now shows me a total of 6 GB RAM. Shouldn’t it only show 3 (or 4)?

  10. Vinoo Thomas Says:

    32 bit Vista SP1 changed the manner in which the available RAM is displayed. Now they show, the physical RAM available on the system & the RAM that is available to the OS. So what you are seeing now is the physical RAM, the OS is still seeing between 3-3.5GB.

  11. sohail Says:

    i have 3.25gb of ram and vista runs smoothly!!
    it boots in 15 secounds!
    i have ultimate installed!

  12. Ry Says:

    yay you

  13. ram addict Says:

    Actually in 32bit vista it does show the ram amount with sp1. However it still does not use all the amount of ram that’s available. This is due to the limitations of the 32bit architecture. What Sp1 does is merely show you what ram is installed on the system. 64bit computing is fast becoming mainstream as 32bit is now showing its age.

  14. akshay Says:

    Hi guys..
    i m using windows vista 64 bit service pack 1 . i installed 4 gb of ram but its showing same as 3.12gb . So its not the matter of 32 bit or 64 bit , moreover service pack 1 didnt able to slove this problem. So if u guys a have any idea pls post or mail me at aks7sach@rediffmail.com

  15. timm Says:

    Re: i m using windows vista 64 bit service pack 1 . i installed 4 gb of ram but its showing same as 3.12gb . So its not the matter of 32 bit or 64 bit , moreover service pack 1 didnt able to slove this problem.

    Very strange! Almost sounds like you are still running 32-bit Vista. I’m running Vista x64 Pro SP1 on an HP laptop and it shows 4GB physical memory via “system information”.

  16. Joel Says:

    Hi guys,

    I bought a laptop with 4GB of RAM and on windows vista displays 3.1. But at the moment is displaying 4GB. Can i configure this manually? Dont know if it’s good but i noticed lower performance in games since then!

    Thanks

  17. Akshay Says:

    Re :: hi timm …. Its not strange man . I m also with the Hp laptop with Windows vista 64 bit SP1 and ya its showing 4 Gb in system configuration but for your information if u wanna check how much your system exactly utilize your ram … type dxdiag.exe in search panel and check there ….. After upgrading to SP1 its fakely showing you 4 gb of ram but actually u able to utilize only 3.12 GB..

    Gud luck……..

  18. Zach Says:

    Thank you for a simple explanation! I really appreciate you taking the time to just state things straightforward like that. You could give Dell lessons.

  19. Thigo Korsakoff Says:

    Good post. I have seen it on my computer too. An increase of memory is always good and improves the performance of other computer or laptop!
    As came to this site, I saw this website below which also deals with the subject!

    http://bargainhere.net/laptop-memory/

  20. Paul Doyle Says:

    I have 4GB of DDR PC3200 (Dual Channel) on my P4-based system (P4 3.4GHz Northwood HT) with Vista Premium SP1 32 bit, Windows 7 beta Build 7000 (32 bit), Windows XP SP3, and Ubuntu 8.10 (four bootable partitions). All four OSes show 3.3 GB of RAM available to my system, so I figure 300 MB more is better than 300 MB less. Also, that 4th 1GB stick acts as a dual channel “place holder”, to keep all my memory running in dual channel mode. If I went to 3 GB (3 sticks), I’d cut the memory bandwidth in half…HUGE performance hit.

  21. Paul Doyle Says:

    I have 4GB of DDR PC3200 (Dual Channel) on my P4-based system (P4 3.4GHz Northwood HT) with Vista Premium SP1 32 bit, Windows 7 beta Build 7000 (32 bit), Windows XP SP3, and Ubuntu 8.10 (four bootable partitions). All four OSes show 3.3 GB of RAM available to my system, so I figure 300 MB more is better than 300 MB less. Also, that 4th 1GB stick acts as a dual channel “place holder”, to keep all my memory running in dual channel mode. If I went to 3 GB (3 sticks), I’d cut the memory bandwidth in half…HUGE performance hit.

  22. Ray Says:

    I have Window Vista Premium software with 3GB memory and 320GB SATA Hard Drive. Is 3GB memory is a lot? How many Software can I program?

  23. timm Says:

    3GB is plenty for Windows Vista. This should allow you to run over a dozen programs at once with little disk swapping.

  24. prefetch Says:

    Vista & prefetch – read about it !

  25. Ant Says:

    Actually, here’s then end-all:

    When running Vista(x32) with SP1, the problem of DISPLAYING the sub 4GB is rectified. OBVIOUSLY it won’t show how much is AVAILABLE; neither does x64. The reason for that is because that number is always changing (don’t believe me? get a digital-style readout sidebar gadget that measures the CPU and RAM usage… That sucker jumps around worse than a hyperactive 10yr old at a Mountain Dew taste-testing convention 😉 ).

    I’ve got a Dual-Core Lamptop (Compaq 6820s) with 4GB (and another GB, via ‘ReadyBoost’), and it runs great… AND it displays that I have 4GB…. I have a portion of that RAM allocated to my ATI card, for gaming.

    Look up the ‘PAE’ command for DOS. There’s an option to help streamline your information, via startup and RAM.

    As well, there are a few apps that run, a la quickstart and TSR, that most people don’t realise are running. Go into and tweak your system startup to free up some additional (read: WASTED) memory.

    And for people who’re wondering: Prefetch = ReadyBooost (Vista’s ability to use USB- and Flash-based memory as a form of RAM.)

  26. Michael Says:

    Hi,
    I have a notebook with 4 GB ram, however I can see only 3GB.
    I heard that I need to install some kind of an update in order to use al my ram. Im using vista home premium.
    Does anyone know anything about this kind of updates?
    Thanks.

  27. Maria Says:

    Hi there,

    I am shocked with this article.

    Facts:
    a) I can not choose the operating system that is sold with the PC
    b) Windows XP will be out of the market soon
    c) PCs are sold with windows vista that not reach 1 GB
    d) Windows vista business requires minimum 1 GB RAM

    Questions:
    Why it´s not the responsibility of firms to sell computers that have memory RAM up the needs of its software?
    Why it´s up to the consumer to ensure that the PC that she is buying has sufficient RAM to run the windows vista? Shouldn´t this be responsibility of the retailer?

  28. RS Says:

    For more detail, see:
    http://www.dansdata.com/askdan00015.htm

  29. gaurav jalan Says:

    man… i m using vista ultimate. and my 4 gb was showing 3 gb in system properties. but as soon as i installed service pack 1.
    guess what ?? problem solved. its showing 4 GB now.
    so dont complicate the simple things..
    cause its so simple to solve difficult things.
    but its so difficult to be simple… 🙂

  30. Ashley Says:

    Never mind how much the RAM is. It is ultimately the Windows wins. I had one gb ram and Vista works slower. and my friend has three gb ram and his system is also having the same speed as mine. Its all because of Vista.

  31. bobmonkey Says:

    My Vista Home Premium recognises all of the 4GB RAM.

  32. Dodo Says:

    @bobmonkey: Then you probably have Vista x64.

  33. Paul Doyle Says:

    “So if a PC has 4 GB RAM installed, some of that 4 GB is used for MMIO. If a PC has only 3 GB RAM installed, the entire 3 GB will likely be available since MMIO typically uses memory above the 3 GB address.”

    “Above the 3 GB address”? This doesn’t make any sense. If a PC has only 3 GB, where “above” 3 GB will the MMIO get mapped? In this example, there isn’t any more memory above the 3 GB. So where does it get mapped?

    Also, doesn’t MMIO need to get mapped on PCs with 2 GB and 1 GB of system memory, as well? In those cases, after the MMIO is mapped, wouldn’t users have the same problem, seeing only around 1.1 GB, and .1 GB, (only 100 megabytes!) of usable memory, respectively?

  34. kmac Says:

    1GB is what windows vista requires as minimum not 2GB.
    Thank-you, Microsoft Tech

  35. Advantages of 64-Bit Windows Says:

    […] Now in August 2010, most of the incompatibilities have been solved as x64 has gone mainstream.  At the local Best Buy today, perhaps 90% of the full-featured laptops run 64-bit Windows 7 Home Premium.  This makes sense because most new laptops come with 4-8 GB RAM, and you must run 64-bit Windows to access more than 3GB RAM. […]

  36. Sage Says:

    Paul, the reason you don’t see this problem with less than 4gb of ram is that there is still addressable space available. If you have 3gb of ram, there is 1 gig of addressable space that can be used for MMIO addressing, without impacting the physical ram. If you have 4gb ram, that MMIO space is going to lower the actual physical ram that you can access.

  37. sabith Says:

    i’ve installed 6 GB RAM in windows server 2003 and in BIOS it shows 6 GB RAM and when i check in windows server 2003 it shows 4GB RAM only ,why

  38. Lewis Says:

    reply to original post, it is possible to run vista on 512MB of RAM, 1gb is better though

  39. Terri Says:

    try msconfig – boot – advanced options – then UNCHECK the MAximum Memory function – also the dxdiag.exe function never lies – the unchecking of the maximum memory function followed by a restart showed full 4GB – not 4GB ( 3GB used ) – this is using Vista Ultimate x64 on an Acer Aspire 6935

  40. venkatesh Says:

    hey i had 4gb ram but it showin 2.75GB is their any problem…………………………plx plx reply

  41. Revitol Stretch Mark Cream Says:

    I belleve the issue has been fixed with one of the more recent updates, hasn’t it?

  42. techienumber1 Says:

    just recently I had to repaire a person’s computer he has vista on it and the ram was their too yet after closer inspection I found that the ram he had was not all th same he mixed 533mhz with 667 mhz after removing the crappy stuff he ended up with about 2GB all 533mhz will people who think they know what they are doing leave it to us guys who have the qualifications and the knowledge please it makes me so angry if you dont know what you are doing then dont do it and if it works leave it alone

  43. techienumber1 Says:

    to add vist runs with out glitches on 2GB of ram running it on 1GB ram will cause errors

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