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Does a motherboard have to support 64-bit or is it just the CPU?

  1. For computer, being 32/64bit is a property of CPU, motherboard, or both?

  2. How do I recognize that "computer" is 32 or 64 bit? I only recongize it by looking if the Windows provided with it are 32 or 64 bit... but that's not ideal.

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marked as duplicate by Ƭᴇcʜιᴇ007, ChrisF, Simon Sheehan, Dennis, music2myear Feb 15 '12 at 22:11

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

    
@techie007, nope, question you cited is one step further - my question is more basic, more general –  Tomas Feb 15 '12 at 20:55
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It's also a good idea to restrict a question to just one question. –  EBGreen Feb 15 '12 at 20:56

2 Answers 2

CPU determines this. However, you can install a 32bit OS on a 64bit processor

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And NOT vice versa. If you're running a 64-bit OS, you have to be on a 64-bit capable processor. –  Shinrai Feb 15 '12 at 20:53
    
Thanks Dave. What do you mean by "CPU determines this"? Do you mean that motherboard doesn't have property of being 32/64 bit? Contrary to what I'd expect (the bus is on the MB also, isn't it?) –  Tomas Feb 15 '12 at 20:58
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The CPU, not the bus does the code interpreting. –  edusysadmin Feb 15 '12 at 21:05
    
"Do you mean that motherboard doesn't have property of being 32/64 bit?" - Yes, just CPU. –  Richard Holloway Feb 15 '12 at 22:06
    
@RichardHolloway, I thought that the 4MB RAM limitation is because some address limitations, which are present on the bus.... aren't they? –  Tomas Feb 15 '12 at 22:46

It's a property of both the motherboard and the CPU collectively. A processor can be either 32-bit or have 64-bit extensions, but it needs a compatible motherboard to plug into. A motherboard could support 64-bit processors, but you could also plug a 32-bit one into it if you didn't need/want/afford 64-bit capability.

For question #2, there are several ways to determine whether the processor is operating in 32-bit or 64-bit mode. As others have commented though, this has been answered elsewhere.

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thanks, so can we say that I can't plug 64-bit CPU into 32-bit only motherboard? –  Tomas Feb 15 '12 at 22:50
    
That's correct. The 32-bit motherboard would likely have been from an older product line, so it wouldn't support newer CPU families that are 64-bit capable. I suppose it's possible for a company to deliberately segment the market by selling 32-bit-only motherboards for cheaper, but pretty much all modern motherboards and processors are 64-bit capable. –  Bigbio2002 Feb 15 '12 at 22:58
    
Thanks. Well, now I have 2 answers that seem to state completely the opposite, so I'm not really sure which one is correct. –  Tomas Feb 16 '12 at 14:01

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