Why can my 64-bit system only use 3.75 GB of RAM, when it has 4 GB and should support 8 GB?

omer May 20, 2010
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I was recently going through my laptop specs when I stumbled upon a surprise. Apparently, according to my 64-bit Windows 7, I have 4 GB of RAM, but only 3.75 GB of it is actually usable.

I was planning on buying more RAM, but now I am not sure. I’m including a Flicker photo to prove it.

Why can my 64-bit system only use 3.75 GB of RAM, when it has 4 GB and should support 8 GB? RAMissue

Can any one tell me what’s wrong with my laptop? It’s supposed to support a total of 8 GB of RAM.

  1. btowne
    February 28, 2012 at 3:24 pm

    Did you end up going to 8GB? I am in the same boat but someone told me Windows 7 64-bit can only see/use max 3.75GB of RAM.. which just dosent seem right.. anyway, did you upgrade, and if so, did it work?


  2. Poxer
    September 18, 2010 at 1:31 am

    Pramoth is Correct it is your on board graphic card that steals a cookie.
    I got this also and the size missing changes depending on how big I make my on board graphic card.

  3. Right processor?
    July 28, 2010 at 8:12 am

    Not all processors are capable of running 64 bit systems. Are you sure yours is? Or is this the preinstalled OS? in which case pay no heed.

    • Oron
      July 28, 2010 at 3:52 pm

      Read the question carefully! The screenshot shows clearly that Omer's PC is running Win 64.

  4. Anonymous
    June 12, 2010 at 5:52 am

    all ram I have seen is in binary measurments (ie 256, 512, 1024, etc.) Hard drives are advertised in decimal (ie 1000 bytes=1kbyte) and you will have less storage than advertised. The OP has on board graphics that is using 256 MB of his memory. If it was a 32 bit system it would show ~3.25-3.5 GB

  5. Sudhan Thiran
    June 6, 2010 at 6:22 am

    Pramoth's Exactly Right,
    This exists in the case of integrated graphics card.
    But if it's a desktop, u can change the quota of allocation for graphics memory.

  6. Pramoth
    June 5, 2010 at 7:46 pm

    I think ur Internal Video/Graphics Cards is taking 256MB RAM

  7. linus
    May 23, 2010 at 10:04 am

    The difference is simply due to the existence of two systems: decimal and binary. Hard drive capacity is measured in the decimal system.


    for a full explanation

  8. Voidoid
    May 22, 2010 at 12:56 am

    I have a laptop with integrated graphics and it shows 4GB usable of 4GB ie I don't have this problem. This infers that some of the proffered explanations are incorrect.

    • pceasies
      May 22, 2010 at 4:11 pm

      It's possible that your system doesn't reserve memory for your IGP and shares it all, or it has separate memory dedicated to IGP only. I believe the Intel 4500MHD has it's own video memory and doesn't use the system memory.

  9. Jim
    May 21, 2010 at 11:23 pm

    yes it is not including the memory reserved on your system for video. i am betting you have an intel video card w/ 256mb memory on your laptop. most laptops use something called shared video memory, which means it uses a portion of your system memory for the graphics. this is why when looking for a laptop most techies will look for one with a separate video card with it's own video memory so as not to take any memory away from the system. shared video is still ok if you are just searching the web but it will restrict the possibility of playing the more popular video games

  10. pceasies
    May 21, 2010 at 7:15 pm

    If you have integrated graphics you may have system RAM being reserved for graphics. Go into the the BIOS and see what's it's set at, it's probably set for 256MB or .25GB, so that's why it's not visible. Any other memory beyond that it might need is shared with the system.

  11. Matt SMith
    May 21, 2010 at 7:10 pm

    the available RAM on laptops can sometimes be deceiving. You need to keep in mind that your laptop will allocate RAM for the video card, unless you have a laptop that has a video card with dedicated memory. This can usually be adjusted in your BIOS, but be careful.

    As far as the HDD space registering a different number, that's a trick of marketing. Technically 1024 bytes make a computer kilobyte (its that rule of 8 thing). But a marketing will just count the bytes as is.

  12. MrT1000
    May 21, 2010 at 6:58 pm

    Usually down to video graphics, you will find that most laptops have an inbuilt video card and not a separate graphics like desktops. The onboard graphics will grab some system RAM, usually from 8mb upwards. In your case it looks like 256mb.

  13. omer
    May 21, 2010 at 9:02 am

    haha haha i was just about to ask about that (:

  14. Taty
    May 21, 2010 at 6:08 am

    Also, you will notice the same thing even with your harddrive space. For example, a 100 gig harddrive usually only has about 95 gigs available.

    • pceasies
      May 21, 2010 at 7:19 pm

      That's because HD OEMs measure 1 GB = 1000000000 bytes
      When actually 1 GB = 1073741824
      so 500 * 1000000000 is how they measure 500GB when it actually is = 465GB plus filesystems have overhead as well (very small, though).

      • K.......
        May 22, 2010 at 11:22 am

        Dude this IS the perfect answer to all your memory Questions..
        1 gb = 1074mb u dont need to worry about extra numbers
        so there is no design flaw or architecture
        those thing only come to servers where they have to power up other many things

        • kosimov
          June 1, 2010 at 2:25 pm

          That's interesting. You stat that 1 gb = 1074 mb, but I always thought 1 gb=1024 mb. Could your number be a typo? If you think it is 1074, please explain, as my engineering degree may be void if so....

        • Aibek
          June 5, 2010 at 1:48 am

          definitely a typo, 1 GB = 1024 MB


        • Primax
          June 7, 2010 at 7:53 am

          Technically this isn't correct. There has been confusion for a long time over kilobytes, megabytes and gigabytes, due to historical computing issues.

          Humans use base 10 for math most of the time, because we have 10 fingers, which was the root of counting. Base 10 means you count until 10, then add a number to the next number up and reset to 0... ie. 9, 10.

          Computers use base 2, for complicated reasons I won't get into here.

          2*2*2*2*2*2*2*2*2*2 or 2^10 is 1024. When referring to bytes, this common counting unit became the kilobyte. This trend continued for years until manufacturers started to use it to represent 1000 bytes, to inflate the size of their goods to customers.

          For many years this was disputed. It was finally settled by the fact that kilo, mega, giga and so forth are base 10 measures, meaning 1000, 1 million and 1 billion respectively. A new set of unit types, kibibyte(KiB), mibibyte(MiB) and gibibytes(GiB) were created to refer to the base 2 representations.

        • Guest
          March 20, 2012 at 7:51 am

          I always thought computers used things like 1,2,4,8,16,32,64,128,256,512,1024 etc. etc. becauseit is easier to display in binary. EG. 1=1, 2=01, 4=001, 8=0001, 16=00001, 32=000001 etc. etc.

    • Toasty O's
      October 13, 2010 at 5:32 pm

      Part of what you are seeing when that happens is "Slack Space"

      It used to be much worse with older file structures, like 16 or 32 bit. On very large hard drives it is still noticeable.

  15. Saikat Basu
    May 20, 2010 at 6:29 pm

    There is always a difference between usable RAM and installed RAM because of the design of the memory (i.e. memory architecture). The other devices attached to the computer (and on the motherboard) also use a segment of the RAM memory and that is what gets deducted from the total memory. Here's the Microsoft support article on a Vista system.

    So, you don't have anything to worry about.

  16. omer
    May 20, 2010 at 6:11 pm

    ohhhhh thank you thank you i was so woried that there was somthing wrong

  17. Steve Campbell
    May 20, 2010 at 5:22 pm


    There is nothing wrong with your laptop. Mine says the same thing. I'm not sure why it saves a chunk of RAM like that but I'm sure there is a logical reason. Upgrading to 8GB shouldn't mean that 3.75 will be usable. It'll probably be more like 7.75.

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