x86 or x64 - How to Know?

Posted on 2012-09-13
Last Modified: 2012-09-15
Hi there.

Just a quick question for something I come across fairly often.

If I have a machine with a failed, formatted or even no hard drive present and I want to re-install Windows, is there any way I can tell from the Microsoft COA sticker whether it is for 32-bit or 64-bit.

Generally they just say for example "Windows 7 Home Premium" - Now that could be x86 or x64 and I don't want to waste time installing the wrong one.

Thanks in advance for any help.
Question by:KTBerwick
    LVL 76

    Assisted Solution

    The COA applies to either version. The only way to know is to check the hardware vendor site for the model/specs. There it will tell you what OS options it comes with. Unless there were hardware issues (no compatible x64 drivers for components, etc. it would have been 32 bit x86) ggenerally it would be x64.
    Checking bios installed memory is another way to tell. I.e. >4GB of ram would suggest the likelihood that the installed OS was x64.
    LVL 10

    Accepted Solution

    Another clue is that any machine that SHIPPED with 4 GB or more would have a 99% chance of having x64.  I believe this is because if x86 was installed there would be a rightful claim of consumer fraud because they cannot use anything over 3 GB with 32-bit Windows.  If a post-shipment upgrade of memory occurred, then obviously this would not be a reliable cue.

    The inverse (less than 4GB) is not necessarily 32-bit, although in many cases it does seem most vendors put on 32-bit.  There is some memory overhead in running 64-bit (mainly larger EXEs), so a machine with 3GB *may* perform marginally better on 32-bit.

    Author Comment

    I have always used the 4GB limit and age of the machine to make a guess. It's usually quite accurate but occasionally you can't tell either way so I hoped there was something more precise. I suppose we will have to keep guessing though.

    Thanks for the help.

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