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Hardware Upgrade: Why Windows Can’t See All Your RAM

ram-header

Installing RAM should be as simple as placing the new RAM into the slots and powering on your computer. However, a number of issues – both hardware and software related – can cause problems when installing new RAM.

Windows should be able to see and use most of the RAM you’ve installed. If Windows can’t see all of the RAM you’ve installed, there’s a problem.

You’re Using 32-bit Windows

32-bit versions of Windows have low memory limits. The maximum amount of RAM supported by a 32-bit version of Windows 8, Windows 7, Windows Vista, and Windows XP is 4 GB. if you have more than 4 GB of memory, you’ll need a 64-bit version of Windows to take advantage of it.

To check which version of Windows you’re using, press the Windows key, type system, and select the System option. (On Windows 8, you’ll need to click Settings before selecting System.)

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If you’re using a 32-bit version of Windows, you’ll need to install a 64-bit version to take advantage of all your RAM.

Your Windows Version Has a RAM Limit

The 32-bit vs. 64-bit difference isn’t the only thing that could restrict the amount of RAM you have available. Editions of Windows also have their own limitations. For example, if you’re using Windows 7 Starter, you can only use up to 2 GB of RAM, not 4 GB. Windows 7 Home Basic Users can only use a maximum of 8 GB of RAM, even if they’re using a 64-bit version of Windows.

For the full list of restrictions on each version of Windows, consult the Memory Limits for Windows Releases page on Microsoft’s MSDN site. You’ll find the name of the Windows edition you have installed in the System window mentioned above.

windows-7-ram-limits

Memory is Allocated to Internal Graphics Card or Other Hardware

Hardware components often use some of your internal system memory (RAM) for themselves. For example, while a discrete graphics card (GPU) comes with its own RAM, onboard graphics (also known as integrated graphics) uses part of your RAM as its video memory.

Your computer may also be allocating part of your RAM to other hardware, such as your network hardware.

To determine how much of your RAM is reserved for hardware and how much is usable by Windows, use the System window mentioned above. The total amount of usable RAM is displayed next to the total amount of memory Windows can see. In the screenshot below, 0.1 GB of RAM is reserved for hardware.

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Your Motherboard Has a RAM Limit

Motherboards also have RAM limits. Just because you can fit the sticks of RAM into your motherboard doesn’t mean your motherboard can use all of the installed memory.

To determine if your motherboard is “seeing” all of your RAM, enter your computer’s BIOS. To do so, restart your computer and press the key that appears on your screen while booting (often Delete or F2). Locate the system information section and look for information on the amount of RAM in your computer.

(If pressing Delete or F2 doesn’t work and you don’t see another key displayed on your screen while booting, consult your computer or motherboard’s manual for information on accessing the BIOS.)

memory-information-in-bios

If your BIOS displays all your RAM but Windows can’t see it, it’s an issue with Windows. If your BIOS doesn’t display all of your RAM, you’re dealing with a lower-level issue.

Consult your motherboard’s (or computer’s) specifications to determine the maximum amount of RAM it supports.

RAM May Not Be Seated Correctly

If you know your motherboard supports all the installed RAM, but it doesn’t appear in your BIOS, you may not have seated the RAM correctly in  when you installed it.

Cut the power to your computer by pressing the switch on the back of your case and open it up. Ensure you’re grounded so you won’t damage your hardware with static electricity. Remove the sticks of RAM and reseat them carefully, ensuring they lock into place properly. If they’re not seated correctly, your computer can’t see or use them.

For more information on properly installing RAM, read: Hardware Upgrade: How To Install New RAM

In some cases, you may have to insert the sticks to RAM into specific slots. Consult your motherboard’s manual for more information.

You may also want to remove RAM – one stick at a time – to determine if a specific stick is faulty and isn’t being detected properly.

RAM May Be Faulty

If you’re having RAM-related issues, some of your RAM may be faulty Download and run a memory-test tool like memtest86 or use the built-in Windows Memory Diagnostics Tool to determine if your RAM is working properly.

If your RAM fails the test, you may want to remove one stick of RAM at a time and re-run the test to identify which is the faulty stick.


If Windows can’t see all your RAM, it’s probably because of one (or more!) of the above problems.

Have you run into any other issues while installing new RAM? Leave a comment and share any other problems you’ve encountered.

Chris Hoffman is a technology writer and all-around computer geek. He's as at home using the Linux terminal as he is digging into the Windows registry. Connect with him on Google+.

  • Published 12/26/12

Comments (29)

  1. Ya

    This seems like pretty good general advice for Linux/xNIX users too. The general rule of thumb I often recommend is that a person doesn’t really need a 64-bit OS unless he/she has 4Gig of available RAM or more AND if they have a particular piece of software that will work better (or even just work) with the new OS.

    Typically, apps like video editors and CAD software will work better with tons more RAM and an appropriate OS like Windows 7 Ultimate. But when it comes to games, it seems that they work better with more balanced components and monstrous video cards but not necessarily with more RAM or even a 64-bit OS. Having that stuff is nice but it can sometimes be a bit like having a formula race car to cross the street. (Can we say overkill?)

    I also liked the passage:If you’re using a 32-bit version of Windows, you’ll need to install a 64-bit version to take advantage of all your RAM. What a mouthful that was! Just install Windows is all it takes? No backups, updates or other considerations like licensing or activation? (Just poking fun.) :-D

  2. NSDCars5

    That reminds me of my favorite computer prank: open it up, and set the RAM to none (ie. pull the stick out).

  3. Abhishek

    Very informative article. Its a good thing to know how much RAM your system can handle before making a purchase or upgrading our PC.

  4. spike

    @Ya: overkill? fast systems are simply more efficient tools. no such thing as overkill, except on the money side, which isn’t related to the current discussion.
    also, 64 bit is the default choice now, not like you refer to it
    also, not sure why you think CAD, etc. perform better with a specific version of windows… actually it could but you got the wrong end of the scale :-)

  5. YB

    I do add that 64-bit *Nix systems also do not differentiate the amount available based on which version of Windows you are using. If you have 192 GB of Ram, all of it is visible to the system unlike if you were in a Windows environment with Home Premium. In which case only 16 GB is visible.

  6. TechnoGeek

    YB: that may be true, but how many people using Windows Home Premium will ever need more than 16GB of RAM? If you’re running a server (something that easily needs a lot of ram), Windows Server is much less limited in the amount of RAM you can use.

  7. thesilentman

    Well, why do we have a RAM limit then? If I didn’t know about Linux, I’d say MS is greedy, but since Linux exists, why can’t 32 bit OSes use more than 4 gigs of RAM? I’m asking for technical details here.

  8. Lelouch

    @thesilentman because the system IS 32-bit. 2^32 = 4294967296 bits. So you can only address up to 4GB of RAM.

  9. boysha

    That is a great explanation: 2^32=4294967296…and I assume Linux has the same look at the math – however, there is a way in Linux to see 8GB or 16GB of RAM on a 32bit system.
    Do you still want to use the same lame explanation?

  10. Zina

    Hey guys & girlz,

    @Lelouch:

    what would you say if Microsoft says that a 32 bit OS can address more than 4GB, eg. 64 GB ;)
    See this article http://msdn.microsoft.com/en-us/library/windows/desktop/aa366778(v=vs.85).aspx#physical_memory_limits_windows_server_2003_r2
    With PAE enabled Windows Server 2003 with 32 bit or AKA x86 can address 64GB (Datacenter & Enterprise).

    OK, probably for playing not the best solution :) – Still would recommend a 7 or 8 edition ;)

    Best regards!

  11. Robynsveil

    That 32-bit Windows can’t see more than 3.1 to 4 gig is best explained here:
    http://blogs.msdn.com/b/dcook/archive/2007/03/25/who-ate-my-memory.aspx?Redirected=true
    That there is such a significant difference between Home Edition and Professional price-wise and capability smacks of money-making scheme: “Pay More, we give you more.” And in Oz, it’s prohibitively more. Thank goodness for Linux – where the only limits are imposed by your hardware, not by some company’s pricing scheme.

  12. TechnoGeek

    thesilentman:
    Another thing worth mentioning is that, just because a *CPU* supports 64-bit addressing (18 446 744 073 709 551 616 bytes = 16 exbibytes) doesn’t mean an OS does, or that even that CPU supports nearly that much RAM to access in the first place… I think we’re still a ways away from OSes (let alone motherboards) that can use anything close to 2^34 GB of RAM

  13. vanahjem

    @ thesilentman

    32-bit OS’es can ‘see’ more than 4 GB of RAM – they just have to use the PAE in the CPU.

    F.x. Win 2003 server enterprise R.2, 32-bit can ‘see’ 64 GB RAM.

    I’m writing this on that OS with 4 GB of RAM and the OS can ‘see’ it all (4191328 K). With f.x. Win XP or Win 7 both 32-bit the OS can only ‘see’ about 3.2-3.4 GB.

    The limitations is for marketing purposes – not technical ones.

    Using PAE gives a very smal preformance penalty and you can not use ‘hibernate’.

  14. LR

    Can I change the amount of memory allocated for graphics card or other hardware?

  15. jpmaya

    Not a problem related to new RAM installation, but to an issue with RAM per se.
    One of my not-so-aged netbooks started to have kinda erratic behavior (sluggish, keyboard inop, etc) and some times when clicking on a desktop icon, a window popping up asking if I’d confirmed to send said icon to the recycle bin turning in loops and locking the whole thing up with no other option but shut it down.
    I ran the Memtest86 and got several issues highlighted red… after replacing the RAM everything went back to normal.
    FWIW

  16. jimhudame

    who still uses 32bit OS’s? 32bit is severely underpowered when coompared to 64bit.

  17. Tom Bettis

    Installed memory (RAM): 16.0 GB (7.93 GB usable), when I had 8G’s installed it showed 4 usable.
    Does it always need half for reserve, or can I change it?

  18. pochp

    Now I’m sure that MS can’t be like a hacker and ‘spy’ on our Windows. And of course I’m glad for that!

  19. jim

    I never seen a 32 bit windows XP system see and use more the 3.5 gig of memory. I always install just 3 gigs

  20. clamo

    “to use the PAE in the CPU” you MUST be using server/enterprise version of windows. this will NOT work on any other 32bit version.

    for gaming you want the faster ram. for computer rendering such as autocad the more the better.
    for choosing the correct memory you need to refer to your computers manual (s) or the mainboard manual. there are a lot of choices out there and IF you don’t get the right type, the ram will not fit/work.

    @jim: yes XP 32bit will see 3.5gigs you need XP 64bit to see 4+

    @pochp: Microsoft can spy on you but if they get caught doing so they are in BIG trouble. like in the past when they did. in the early 90′s they were checking users computers for legitimate keys and they got caught.

    @Tom Bettis: sounds like something is wrong with your mainboard or you have WAY to much loading up @ start up.

  21. vanahjem

    @ clamo

    “to use the PAE in the CPU” you MUST be using server/enterprise version of windows. this will NOT work on any other 32bit version.

    Yes, that’s true – and part of my point.

    Most of the code is the same from ‘starter’-versions to ‘ultimate’-, ‘server’- and ‘enterprise’-editions.

    MS just inserts different limitations on the different versions – f.x. for win 7 – ‘starter’ < 2 GB, 'Home premium' < 8 GB, but all 32-bit systems could use ~ 3.5 GB if allowed and all could use up to 64 GB if PAE is used. Also servereditions is limited in this way – f.x. win 2003 webserver, 32-bit can only use 2 GB.

    It's an ageold trick – IBM decades ago sold 3 'different' officecomputers with different software at different prices and different speed.

    The reason for the difference in speed was not the hardware, as is was identical (unknown to the byer), but the software (OS?).

    In the 'big' model al was as it should be.
    In the 'middel' model a counter was set to count to 1000 at a central point in the software.
    In the 'little' model the counter ran up to 5000.

    Viola – you have 3 'different models' at different prices for different budgets, but you only have to develop one machine and one OS.

    On sight we of course have to go over to 64-bit, but it's 'interesting' that you are locked to 32-bit and must pay for a 64-bit version of the same OS if you want to use more than 4 GB in your old machine bought with OEM-windows 32-bit.

    PAE have been part of CPU's the last decade or more…

  22. Spike

    Thank you How-To Geek! I always wondered why when working on computers running x86 with 4GB RAM it randomly says 3.25GB Usable or sometimes 3.75GB Usable, which I now know is due to reserving for hardware. My question is though, if that’s the case howcome when installing a x64 bit version of Windows the full 4GB is usable and there is no reserve for hardware?

  23. Spike

    Thank you How-To Geek! I now officially know the reason why when working on computers running x86 with 4GB RAM it randomly says 3.25GB Usable or 3.75GB Usable, because of it reserving for hardware. Although, why is it if you had to install x64 bit version it will show the entire 4GB of RAM being usable and not 3.25 or 3.75? Surely irrelevant of architecture there should still be a reserve for hardware?

  24. Dean

    I’ve read some articles lately, researching how to make my system use available RAM rather than being so CPU intensive when processing and converting a database. Those articles asserted that a 32-bit system could use more RAM than the 4 G limit by making a RAMdisk. That concept, at least, has been around since DOS 6.2, if I recollect correctly.

  25. axegrrl

    > I never seen a 32 bit windows XP system see and use more the 3.5 gig of memory.

    See “Memory is Allocated to Internal Graphics Card or Other Hardware”. That last 512MB is most likely being allocated to the graphics card.

  26. JungleBoi

    @Ya: Welcome to the 90s!

  27. SargentTNT

    WHO USES 192GB OF RAM u would have to have a supercomputer to use it

  28. SargentTNT

    Now I know why my 8 gigs of ram has only 7.9 gb for windows 8

  29. Paul

    I have a very nice HP Pavilion Elite Quad Core using Win 7 (soon to upgrade to Win 8) that has 8GB of memory (4 slots with 2GB ea.), with a Radeon 3650 graphics card (very good, but also soon to be upgraded). I can burn a copy of a DVD movie in approximately 26 minutes, start to finish. After the first, additional copies are about 8 minutes. I have several questions: First, if I were to add the additional 8GB to total 16GB Win 7 Home Premium max out, would this increase my multitasking capability (which is already excellent), and would this serve to speed up my burning? Secondly (or not necessary depending on your answer to the first question), are 4GB memory cards available on the market so I could do a 4×4 configuration? Next, my current memory is DDR3. Can I upgrade this to DDR5 when and if I go to 16GB?–or must I stick with the DDR3 that came with my system? and finally (whew!), If I do these upgrades, should I do them before I upgrade to Win 8 or does it make any difference at all?

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