Clarification about 4GB ram and Windows XP 32-bit

By jothanan
Dec 16, 2008
  1. Hi to everyone reading this,, just wanted to ask something.

    i currently have 2GB of ram (2pcs of 1GB stick), and i plan to buy another 2GB. i heard that only 3GB-3.25GB will be identified by the OS.

    now, what is that 3.25GB, Total PhyMem or the Available PhyMem?

    cause now,,when i look at the System Information, my Total PhyMem is 2,048MB and has an Available PhyMem of 1.36GB.

    what do u think would be my Total and Available PhyMem after buying another 2GB of RAM? and what would be the best thing to buy, 2 pcs. of 1GB or a piece of 2GB stick? again, i have 2pcs of 1GB currently installed. thanks in advance to anyone.^^

    and another thing, increasing RAM also increases FPS of today's games right?
  2. kimsland

    kimsland Ex-TechSpotter Posts: 14,524

    You have the maximum amount of Ram that Windows Xp 32 Bit can use already (2Gig)
    ie no need to purchase any more

    When you see "Total PhyMem is 2,048MB and has an Available PhyMem of 1.36GB".
    This can be a tad confusing. Physical Mem is 2048, but available depends upon:

    what your PageFile is set to + your physical Mem - Used Mem = Total available Mem

    As each persons PageFile is different, and even variable by Windows, we'll never get a truly accurate amount of what your used Ram is.

    Is that confusing? Woops, I mean clear?
  3. direwolf007

    direwolf007 TS Rookie Posts: 105

    It would be total PhyMem. It is hard to say how much availiable memory you will have, since I do not know what your computer runs at startup, etc.

    2x1GB would be best due to ability to run in Dual Channel mode, but the advantages of DC mode are not significant. Also, remember, some motherboards dislike specific memory configurations and even though these are not very common it is better to check the documentation for supported memory configurations.

    Finally, increasing RAM does not impact today's games very significantly, you can expect a scant few more FPS and less FPS drops, but you won't notice the difference in all but the most demanding of games.

    A little technical explanation:
    The reason for a 32-bit operating system seeing only "3-3.25GB" of RAM is because 4GB is the maximum number of different memory addresses which can be represented in 32 bits. Since the operating system also maps some other memory into this address space (video card memory and the memory of other PCI-E devices, if any, for example - among a plethora of other things), it cannot map the entirety of the RAM for its own use. Thus, the end result is the OS being able to utilize less than 4GB of RAM. This is the reason for seeing less than the real 4GB RAM installed in "Total Physical Memory".
  4. jothanan

    jothanan TS Rookie Topic Starter

    Yeah i understand. thanks for the reply. but i really plan to upgrade RAM, yeah, for modern gaming purposes. i am now satisfied with the Graphics when i play these games, but im not satisfied to the FPS i get. and im thinking that upgrading my RAM would give me a decent increase in FPS, and thinking that RAM is now more cheaper than before. i would love to have that 3.25GB of ram even what i bought and installed is 4GB ram. so having "System Information" as our basis,, what would be my Total PhyMem and AvailablePhyMem after adding another 2GB of RAM?
  5. direwolf007

    direwolf007 TS Rookie Posts: 105

    This does not sound right. While true that a User Space program in WinXP 32-bit can only use up to 2GB of virtual memory space (and it can be reconfigured in the boot.ini file to 3GB), more than 2GB of memory will be utilized by the Kernel and other programs.
  6. kimsland

    kimsland Ex-TechSpotter Posts: 14,524

    Oh you want me to find this info and quote it?
    Yes I'm right. Yes Windows Xp 32 bit uses up to 2gig in one single process, and that's that. And it can't use any more on another process
    I already wrote all this before, I don't want to look it up, but will if everyone starts saying no, then I'll have to. I've spent hours and hours on this one subject (more like days)
  7. direwolf007

    direwolf007 TS Rookie Posts: 105

    1) I would very much like to see your info.
    2) You can allocate more than 2GB to a process (assuming it was compiled with the appropriate flags which allow it to use more than 2GB of memory) by reducing the memory reserved for the kernel itself with a boot flag.
    3) Even if you cannot use more than 2GB of RAM in a process, then having extra physical memory will allow all of the process' 2GB of allocated memory (if it uses 2GB, otherwise the discussion is pointless anyway) to reside in the memory alongside the memory consumed by the kernel. In either case, this leads to a performance increase, but as I stated, it is not very significant in most cases.
  8. kimsland

    kimsland Ex-TechSpotter Posts: 14,524

    I made the post on another forum tguy (abbreviated) where I had 1000 posts (a tenth of now ;) )

    But I'll just get the official stuff
    Please ask at Intel in the mean time, by the way, this has nothing to do with hardware, but there's probably some old guy there that'll have the info straight up, for you
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