Computer seems to detect only 3GB of ram

By MattTheTubaGuy
Jun 18, 2009
  1. My computer, (os Windows Vista premium), seems to only detect 3GB of RAM for some reason. In Task manager, it shows the total memory as 3069MB, even though the Setup Utility shows that I have 4096MB.
    Also using Autodesk Inventor, it crashed when there was still more than 1/2 a GB of ram left because it ran out of memory, which seems strange.
    Is there a way of fixing this problem?
  2. snowchick7669

    snowchick7669 TS Maniac Posts: 660

    Here's something you may find interesting and explain as to why it is only addressing the 3GBs of RAM.

    Basically you need a 64bit operating system to recognise more then 3-4Gbs of RAM. The link above will explain the differences between both types of OS
  3. Tedster

    Tedster Techspot old timer..... Posts: 6,000   +15

    32bit operating systems can only address around 3GB of RAM. To use more you will need a 64bit OS.
  4. T77

    T77 TS Enthusiast Posts: 300   +6

    Yeah u need a 64bit os,theres no point of having more than 3gb of ram when u r using a 32bit os
  5. red1776

    red1776 Omnipotent Ruler of the Universe Posts: 5,219   +157

    Hey Matt,
    the short version is that it is something called MMOI, memory mapped I/O reservations, its an architectural design and decision made long ago when the idea of having a full gig of ram was thought to be preposterous and would not ever happen or be needed. in a 32 bit os it lets you use somewhere between 2.75 and 3.25 Gb of 'working memory' and reserves the rest for things like pci buses, installed hardware, etc. the other Gig is there, you just don't get to use it as working memory. hope that wasn't to much babbling :)
  6. Justin

    Justin TS Rookie Posts: 942

    The posters above have mostly covered it, but another point to bring up is the Kernel/Application memory split. On 32-bit editions of Windows XP/Vista, there's an upper memory limit of 2GB that programs can actually take advantage of. Without modifying your OS, you will get severely diminishing returns on memory sizes >2GB as the Windows kernel will reserve that extra memory solely for itself/Windows executive processes.

    You can read more here:

    So really to take advantage of 4GB of memory, you'll need to switch to a 64-bit version of Windows.
  7. red1776

    red1776 Omnipotent Ruler of the Universe Posts: 5,219   +157

    great point Justin,
    there is a program, software, that will let a program (say photoshop,etc) access more than the two gigs.
  8. captaincranky

    captaincranky TechSpot Addict Posts: 11,467   +1,760

    Just so we're clear, M$ indicates that the "3GB switch" can only be applied to XP >Pro< and server editions.

    Are they lying? Dunno.
  9. red1776

    red1776 Omnipotent Ruler of the Universe Posts: 5,219   +157

    Im not sure, i never used it but i have heard others claim that they have done it with XP as well.
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