32- or 64-bit?

Discussion in 'Computer Information' started by Jeff Strickland, Aug 26, 2012.

  1. I have a home-built machine that has 8GB of RAM installed, the BIOS reports
    all of the available RAM.

    Windows XP only reports 4GB of RAM.

    I understand that 32-bit operating systems can only utilize 4GB, and a
    64-bit system is needed to see (and make use of) any RAM in excess of 4GB.

    My question is if the processor that I have is a 64-bit processor, or not.

    What I am running into is the cold, hard fact that XP is no longer supported
    in the very near future. This means I will be forced into Win7, whatever,
    and I may as well use the 64-bit version of the OS if my processor has the
    capacity to do that.

    So, the BIOS of the current installation reports all 8GB of available RAM,
    while the XP Pro, 32-bit operating system reports the limits of the OS.
    Since the BIOS sees all of the installed RAM, does that mean the board and
    processor are capable of handling a 64-bit OS?
    Jeff Strickland, Aug 26, 2012
    1. Advertisements

  2. Jeff Strickland

    Paul Guest

    Intel has the Intel Processor Identification Utility (PIU). There is
    a Windows installable version.

    Intel has ark.intel.com. You can find your processor there, if it's Intel,
    and see whether it says "Instruction Set: 64 bit".


    AMD has products.amd.com for their processors.

    There are a couple modes a 64 bit processor can use. The most common mode
    for a home user, might be mixed 64 bit/32 bit, where both 64 bit or 32 bit
    programs can run. But I think there's some other mode, where the processor
    runs in pure 64 bit mode. Maybe some day, on some future OS, they'll select
    that mode.


    PAE mode, has existed for years. It allows up to 64GB of memory, to be accessed
    in 4GB blocks. When you run an individual program, it can access things in that
    4GB chunk. But not access all of the memory. And that can be done by a 32 bit
    processor. So in fact, even with older processors, in theory, a 32 bit
    processor could access a much larger block of memory (even if they didn't
    have big enough DIMMs back then, for it to matter).

    If the BIOS wanted, it could use such a mode, to implement a memory test
    of a 8GB memory space, using nothing but a 32 bit processor. Simply
    reload the page table, and test the second half.

    Inside the processor, a 32 bit address runs through the TLB or page tables,
    and a 36 bit address comes out as the answer. That's traditional PAE. That can
    be used to address more than 4GB of memory, as long as the Northbridge has
    a 36 bit address bus. There have been some Intel chipsets, where Intel could
    have easily provided the extra 4 bits, but chose not to. In that case, only
    32 bit addresses flow from processor to memory controller. In such a case, you
    can install 4x2GB of DIMMs (since the row/column address on the Northbridge
    is capable of doing it), but, since only 32 bit addresses come in over the
    FSB, only 4GB of the 8GB can be addressed. That may have been back in the
    LGA775 era. (In other words, limited addressing can be caused by the motherboard,
    but the situation is pretty uncommon.)

    Later processors, both Intel and AMD, the memory controller is inside the
    processor, so there is less of an excuse to be bottlenecking the address bus.

    On AMD, I think addresses can be at least 40 bits (for things like PAE),
    which surpasses the ability to find big enough DIMMs to cause a problem.
    Part of the reason for AMD to support such a number, is the ability to build
    server designs with multiple sockets, and "coherent" interconnect. Any processor
    in that case, can read the memory on any other processor, via Hypertransport.
    A thing like a 40 bit address, would be handy for addressing such a larger space.
    Desktops typically don't have multiple sockets (any more), but AMD tends
    to maintain architectural parity between desktop and server designs. Same
    applies to AMD supporting ECC on desktop memory - ECC is a server feature,
    and they try to keep some of those features common across the entire product

    So if you have an Intel processor, you can play with the PIU program.

    If you have an AMD processor, you're going to have to work a bit harder.
    Find a hardware utility that can identify the processor. Run the identity
    through products.amd.com (or search against cpu-world.com), and get
    the particulars.


    One cold hard fact, is you don't need Microsoft to be patching your OS.
    I occasionally use Win2K, and it hasn't been supported in some time, and
    the old programs loaded on the machine for it, still work. How Microsoft
    works their magic, is giving software development tools to developers, that
    magically don't work on older OSes, and that's how they "wedge out" the
    older OSes. Microsoft destroyed 3D game compatibility, so that new games
    wouldn't load on Win2K (even though Win2K and WinXP core are very similar),
    and that's how they "encourage" you to leave the old OSes behind. If it wasn't
    for that sort of thing, you could quite comfortably continue to use it.
    The AV companies already know how to build product for the older OSes,
    so they can still provide you with a measure of protection.

    There's a contingent of people still using Win98, as an example of
    how far you can go with this.

    Paul, Aug 26, 2012
    1. Advertisements

  3. Jeff Strickland

    - Bobb - Guest

    AS for 'what type CPU do I have?"
    - control panel - system -
    hardware- device manager - Processors
    will display the model

    I have "AMD Athlon64 Processor 3200"

    When AMD first came out with 64 bit 'Hyperthreading channel, MSFT and AMD
    did a road show for an OS called X64. It ran in 64 bit mode on AMD. At the
    time I was on a team that went to the shows and we could buy the motherboard
    and X64 bundle for ~$200. I bought one but even thought WINDOWS and the
    hardware might be 64 bit, the Program must be written to take advantage of
    the 64 bit OS. If it isn't, CPU runs simply run in 32 bit mode. I found the
    only real market for it were pro workstations. They'd buy a solution from a
    bundler ... say Parametric Technology's Pro Engineering program. For that it
    would run in 64 bit mode and worth the money, but if your app is only
    written in 32 bit mode, it can still only see 32 bits.

    I think you'll find that even though you buy a 64 bit CPU, MOST programs
    will still be written for a 32 bit world. UNLESS that much memory is
    required to run the program ( 3D designing etc)

    AS for 'not being able to use the AMD processor, check here for updates :
    - Bobb -, Aug 27, 2012
  4. My goal is to move toward an OS that still has support, and will have for
    many years to come. I already have an OS that support is about to die out
    on, and any information that leads to even older OSs is not meaningful or

    So, I have a motherboard that is stuffed with two 4GB RAM modules, and the
    BIOS reads the correct total but the OS (XP Pro) only reads half.

    My specific question was if I happened to have loaded a 32-bit OS onto a
    board that has the capacity for a 64-bit OS.

    The reason the question comes up is because the board is relatively new and
    meets my needs for speed and quantity of the various ports, but if there is
    a failure that demeands reloading the OS, then on that event I would likely
    invest in the current OS and I was wondering if I could automatically select
    the 64-bit version, or should I get the 32-bit version.

    I'm not interested in making my current OS do anything more than it does
    with respect to the memory capacity. I simply had a brain-fart when I built
    the system because the motherboard could support 2x4GB of RAM, and the price
    was right -- well, it was okay -- so I bought it. I realized the error of my
    ways when I started assembling the parts, but there is no harm in having
    8GB, but only 4GB are being used. The HDD took a dump -- warranty coverage
    available -- so I had to replace it. It is becoming a struggle to reload XP
    because of all of the updates and the arguments with the Genuine Advantage
    verifications and so on. As I figure out how to game the system so that I
    can get the machine going, I find that there is a warning on Microsoft's
    Website that says support for Win XP will be ending soon.

    In the interest of planning ahead, I will be upgrading to Win7, or perhaps
    Win8, in the not-so-distant future, and I was wondering if I could go to a
    64-bit OS since the motherboard knows how much RAM is installed. I don't see
    any point in staying with a 32-bit OS that can't work with more than 4gb of
    RAM when there are 8gb of RAM installed. I guess my question is about my
    confusion as to whether the amount of RAM that can be seen is a function of
    the motherboard or the operating system. I don't recall at the moment
    whether the CPU is an i3 or an i5. If these are 64-bit, then I will get the
    64-bit version of the next OS that I have to buy.
    Jeff Strickland, Aug 27, 2012
  5. Jeff Strickland

    Paul Guest

    Use Intel PIU utility, to confirm the processor model number.


    Then go to ark.intel.com and look up that processor number.

    A 64 bit processor, can run 64 bit or 32 bit programs, or
    install a 64 bit or 32 bit OS.

    Memory addressing is a separate issue. If you install a 32 bit OS,
    PAE mode (supported in hardware for eons), *could* support all 8GB.
    But the Microsoft memory license prevents you from doing so.


    With a 32 bit OS install, and the Microsoft memory license in place,
    you *can* still use the additional RAM above 4GB. But you can
    only do that from ring0 driver space. With this software installed,
    4GB is for the OS, and the other 4GB goes to a RAMDisk. And that's
    with a 32 bit OS (one that is actually running PAE mode, for other

    RAMDisk freeware...


    In summary, if you have a 64 bit ptocessor, you can do anything you
    want with it. It supports 64 bit or 32 bit programs. Microsoft
    can impose a memory license or not. The chipset can be a limitation,
    but when I hear you mention "i3 or i5", that tells me the chipset
    is probably not a limitation in this case.

    Paul, Aug 27, 2012
  6. Jeff Strickland

    - Bobb - Guest

    I do have a Win7 Pro 64 machine but I only have 3gb installed in that box so
    limits not an issue for me. I figured it gives me option to expand if needed
    although I can't imagine I'd need it. As you might know, licensing of the
    program is the limiting factor. Are you just going to run IE, MSFT apps
    designed for this new OS ? To go from XP to Win7 you'll be reinstalling. If
    there are some programs that you now have and THAT is why you want to see
    all 8gb, check specs to see if it will even run - in what environment. You
    will probably see that the license is for a 32bit Windows environment. The
    old programs will only run in 32 bit mode even if you had a terabyte of
    memory. So although Windows might see the terabyte, the app will still run
    in its little world .. pagefaulting - quickly, but program still will only
    see what was designed for. Unless a need to have many apps in memory,
    perhaps consider buying another motherboard/cpu for the Win7 pc - use 4gb
    there and keep current pc. That's what I've done with a few of my pc's. I
    always overbought and ended not 'needing' the horsepower. That's why I'm
    still on the old PC right now - it still works fine with just 1gb left in
    it. I couldn't justify tossing it.
    - Bobb -, Aug 28, 2012
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.