Why Can’t I see all 4GB of RAM?

Ever since I created this post about the real memory maximum in Windows (including Windows XP and Windows Vista, and any 32-bit version of Windows), I get A LOT of questions about it. I thought I’d take a minute to answer some of them:

Hello

I just wanted to find out why my asus board p5w-dh-d picks up 4gigs of memory in the bios but only 2gig in windows vista business 32bit

Thank you.

Answer: Read this post. That’s just the way it works. Sorry.

and (more after the jump)

Does all this mean that on a Dell M1710 with a 512mb video card, Vista Ultimate (32b), and 2GB of Ram, one is likely to see only 1.4 GB of RAM or less, since Vista needs to match the video RAM allotment with RAM memory?

Answer: No, your maximum RAM is 4GB minus any RAM required by your video card. So, with 2GB and that video card, you’ll still have access to all 2GB. If you had 4GB and that video card, you’d probably only see 3.4GB.

Also, does having a 4GB or higher ReadyBoost enabled USB drive help in any of these metrics, be it on a system with 2GB of RAM or 4 GB?

Answer: It does help performance, but ReadyBoost acts as a disk cache. It won’t affect your maximum memory. and

Hello, I just read your response to the maximum amount of RAM you may actually be able to use in an XP Pro 32bit System. I know your busy but if you have a chance to address my question it would set my mind at ease.

I have an ASUS mother board PLN5SLI, lower end but it is capable of supporting 4gb of DDR2 Ram. My system is only utiliizing 2.75GB of it.  What I gathered from your responses was that my BIOS and what not will take up a certain amount of ADDRESS Space and also my video cards. I have 2 BIOSTAR 256mb DDR2 PCI-E video cards running in SLI mode, so right there i’m down about a gig because of the needed ADDRESS SPACE for the actual BIOS, I/O, PCI slots…… and the cards.

So with my system as it is I will NOT be able to get anymore than about 2.75gb of RAM.

system info:

  • p4 – 2.66 Ghz processor
  • ASUS PLN5SLI mobo, 4gb ram, SATA headers(2)….
  • BIo Star nvidia gforce 7300.. 256mb DDR2 SLI Ready Video Cards PCI-E
  • 4gb DDR2 RAM
  • Diamond 5.1 Audio Card

I hope this isn’t too much noob talk for you I’m enthusiastic about building PC’s but have a bit to learn as well.

Answer: Yep, you won’t be able to use more than about 2.75GB. You might as well take the rest of the 4GB out. Sucks, I know.

and

Hello,

I read your article on Maximum Memory in 32-bit Windows (http://www.vistaclues.com/reader-question-maximum-memory-in-32-bit-windows-vista/)because I just purchased a new computer from Dell with 4GB of RAM and running Vista Home Premium (32-bit edition).  My system seems to only have 3.0 GB of RAM available.  The BIOS sees all 4GB of RAM, and upon discussing this issue with Dell Tech Support I only got the vague response “It’s used for a lot of I/O functions”.

My processor (Intel Core2 Duo) supports the 64-bit versions.  Should I look into an upgrade?  I’m no expert on these things, so I wonder whether I’ll see much benefit from the inevitable pains of many software incompatibilities.

Thanks, and I will look to your site in the future for many of my technical issues, as they’re explained very clearly.

Answer: Yeah, it sucks that Dell doesn’t warn you that you won’t be able to use all 4GB of RAM with 32-bit Windows. Should you upgrade to 64-bit? No, probably not. Read this article about choosing between 32-bit and 64-bit to be sure. 

This entry was posted in Featured, Hardware, Reader Questions by Tony Northrup. Bookmark the permalink.

About Tony Northrup

Tony Northrup, MVP, MCITP, MCPD, MCSE, MCTS, and CISSP, is a Windows consultant and author living in Waterford, Connecticut, in the United States. Tony started programming before Windows 1.0 was released, but has focused on Windows administration and development for the last fifteen years. He has written more than two dozen books covering Windows development, networking, and security. Among other titles, Tony is coauthor of the Windows 7 Resource Kit, the Windows Vista Resource Kit, and Windows Server 2008 Networking and Network Access Protection (NAP). When he's not writing, Tony enjoys photography, travel, and being awesome. Tony lives with his girlfriend, Chelsea, her daughter, Madelyn, and three dogs. You can learn more about Tony by visiting his personal website at http://www.northrup.org and his photography portfolio at http://northrupphotography.com.

12 thoughts on “Why Can’t I see all 4GB of RAM?

  1. Pingback: Reader Question: Maximum Memory in 32-bit Windows Vista - Windows Vista help

  2. I have the same problem, after spending nearly £400 on 4GB of high performance DDR2 memory – Microsoft’s latest and greatest can only see 2GB and the 64-bit vista makes most of my peripherals redundant – what a load of sh*t – after all its 2007, Vista 32bit should be able to see 4GB – so why can’t it – why do so many people have to resort to forums to find solution/cause of such a common problem – surely Microsoft should be forced to produce precise answeres to these problems – you would think seeing the amount of physical memory available is one of the simplier comms between hardware and software.

  3. Hello there,

    I have the same problem i thing…
    COmando Asus MB
    4GB Ram/800
    Nvidia 8800GTS..

    Any help?

  4. @paul: If you would know how memory addressing works, you would know that it is not about “seeing all the memory”. Vista is fully aware of the 4GB but there are other things that have to fit into that 4GB.
    This is not Microsoft’s fault. 2^32 = 4GB, that’s why you should use a 64-bit OS with 4GB RAM.
    (MS even explains why it doesn’t use PAE to overcome that limitation in its 32-bit OSs)

  5. Blame vista right away huh? Have you looked to see if your BIOS is showing the 4GB installed?

    Vista addreses 4gb. That’s it. Mac OSX too. If your bios can see the 4gb and you have 512mb of vram, then you’ll see 3.5GB. 32 bit operating systems are limited to 4gb. you can;t break the laws of physics people.

    Get Vista 64 if you need to see ALL your RAM.

  6. Oh here is a concept for ya…..tell the end user that if you install 4g of memory in a 32bit operating system, you will only see (x) gb due to the following reason… so that the end user doesn’t spend the money on the product prior to finding this out. And in order to know this prior to his purchase he has to be an above average system educated individual. Is that too much to ask for? Truth in advertising. The manual for the system only states that in a 32 bit supported envirnment you can upgrade to 4g, and in a 64 bit environment you can upgrade to 8g. Right below this statement should be the explaination. But, we can’t expect that because it would affect the sales of unused components…

  7. I’ve been using my Vista Utimate 32-bit with 2GB so far but since I work a lot in Photoshop CS3 I decided to buy another 2GB (now I have 4x1GB, all 667).

    I see 4GB in my BIOS but only 2GB in Vista. Photoshop doesn’t see more either (I am actually able to use about 1,5GB in PS). So I downloaded Vista Service Pack 1 and now I can see 4GB in my Vista as well but Photoshop still shows about 1,5GB. Does that mean nothing really changed… I was hoping to get some extra memory…

  8. I built a dual FX-74 system with a L1N64 mobo-2 Ge-force 6600 OC 512 vids… My issue is vista only sees 1gb of pc6400 800mhz ddr but when i check it out with PCwizard it shows the full 3gb “3x1gb sticks” ? and if i try to install the full 4 sticks the system wont even post?

    Why wont vista even see the 3gb? i understand the issue with not seeing more then 4gb-np but only 1gb?

    Is there anything i may have missed in bios or tweaks to get vista to see the ram?

  9. The first question is very similar to my problem. I got a barebone that has no gfx card other than the onboard Intel chipset graphics or anything else in it. The BIOS can see 4GB memory and so can CPU-Z but Vista Ultimate x86 says only 2GB. If I go into the BIOS and change “Memory Remap Feature” to enabled then Windows will see 2.8GB.

    Now, my other machine has 4GB memory and a 8800GTS and on that machine Vista can see 3.2GB.

    I did research before I got the memory. Asus and Kingston says that 4GB should work so why the **** doesnt Vista play ball???

    I am installing SP1 on the first machine. The second one could see 3.2GB before I installed SP1 on it so that hasnt changed.

    It really doesnt make sense to me.

  10. Wow I love posts from people that state things in such a matter of factly way and yet they are still wrong. The Dell M1710 has an Nvidia graphics card that is separate from the motherboard and is also independent from the ram. This meaning your 512mb of video card either 7900 GT/GTX or 7950GTX is a independent card with its own 512mb of Ram. Thus your bios sees all the ram that is there, but you are correct about the 32bit OS having memory header limits to addressing the full 4GB. Other laptops, not gamer ones especially, have ram dependent graphics cards, In their bios there is most likely a section to select how much ram is designated to the video card. Then when you change that setting you can view that exact amount taken away in windows. Check your buddy’s HP laptop if you don’t believe me.

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