32bit vs 64bit is a property of CPU, motherboard or both?

Question

Possible Duplicate:
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.

Solution 1

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.

Solution 2

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

Comments

[Tomas]

@techie007, nope, question you cited is one step further - my question is more basic, more general

[sean christe]

It's also a good idea to restrict a question to just one question.

[Tomas]

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?)

[edusysadmin]

The CPU, not the bus does the code interpreting.

[Richard Holloway]

"Do you mean that motherboard doesn't have property of being 32/64 bit?" - Yes, just CPU.

[Tomas]

@RichardHolloway, I thought that the 4MB RAM limitation is because some address limitations, which are present on the bus.... aren't they?

[Tomas]

thanks, so can we say that I can't plug 64-bit CPU into 32-bit only motherboard?

[Richard Holloway]

Ah the 3GB problem! Have a look at en.wikipedia.org/wiki/3_GB_barrier and the section "Chipset and other motherboard issues"

[Bigbio2002]

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.

[Tomas]

@RichardHolloway, no no, please don't focus on RAM, I'm just asking: are you sure there is no bottleneck in the motherboard, that would disable the 64-bit CPU functionality?

[Tomas]

Thanks. Well, now I have 2 answers that seem to state completely the opposite, so I'm not really sure which one is correct.