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Like what the topic says: What is the difference between 64-bit, X64 and "dual core"? I read on some software (Win2K8R2) system requirement, it says the system should be X64 or dual-core.

I thought I knew what was X64, but now I think I don't anymore. Can someone explain the differences/equivalence? many thanks!

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migrated from Dec 24 '10 at 8:31

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There is no real link between x86-64 (or AMD64) and dual core, aside from the fact that they emerged into the world around the same time, there were dual-core 32 bit processors from Intel and single core AMD64 processors around for a while. I suspect requirements that list one or the other are basically just saying not to use some stone age processor that Noah would be familiar with. – Mokubai Dec 24 '10 at 9:05
up vote 9 down vote accepted

64-bit is a fairly generic term that is usually used when referring to a system, component or software that can operate on items (integers, memory locations, etc) that are 64bits long in a single operation.

x64 (or x86-64, or AMD64, or Intel 64, also previously know as IA-32e and EM64T) is an extension to the x86 instruction set, providing support for 64-bit registers, memory space and the like. It is fully backwards compatible with the 32-bit x86 instruction set (allowing 32-bit software to be compatabile without modification in most cases) and is usually taken to simply mean a 64-bit instruction set.

However, a processor that impliments the x64 instruction set is therefore 64-bit, but the opposite is not true - there are other 64bit instruction sets - so the two are not synonyms (although, as said, they are sometimes used as such in the home user computing market).

Dual core (or more) simply means that the processor provides two (or more) distinct physical cores to allow the processor to work on multiple tasks concurrently. Software that is designed to take advantage of multi-core processors will usually operate faster, software that is not programmed for this advantage or that have bottlenecks elsewhere (ie, network or hard drive access) will not be improved in most cases.

A processor can be multi-core and not be 64-bit, and conversly a single core process can be 64-bit (of any 64-bit instruction set). Number of cores is entirely unrelated to bit-ness.

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64-bit - means something which supposed to work with 64-bit integers/memory addresses.

x64 - processor architecture which can do 64-bit calculations & memory addressing natively.

Dual core - means that there are 2 physical processors on 1 dye, which give you double speed for some of the tasks.

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Two physical processors on one die. – Ignacio Vazquez-Abrams Dec 24 '10 at 9:01
You right...... – BarsMonster Dec 24 '10 at 9:07

The term x64 means the same thing as 64 bit referring to processors, but as Ignacio Vazquez-Abrams pointed out there are processors (not Intel or AMD) that can be 64 bit but not x64. If we are talking about mainstream PC processors (Intel and AMD) I would not be afraid to use the terms interchangeably.

The term dual core means just that, two cores. These days it is safe to assume that a dual core processor is 64 bit. Back in the day however there were a few Pentium processors (T2060, T2080, and T2130) which were dual core but were not 64 bit.

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Not quite correct. There are plenty of 64-bit processors that are not "x64". – Ignacio Vazquez-Abrams Dec 24 '10 at 9:08
@Ignacio Vazquez-Abrams not sure I follow, could you elaborate (maybe provide an example of one of the processors you are talking about)? – ubiquibacon Dec 24 '10 at 9:25
Alpha AXP, MIPS64, UltraSPARC, PowerPC, and soon ARM. – Ignacio Vazquez-Abrams Dec 24 '10 at 9:26
Sparc, PowerPC, and Itanium to name a few. – Jimmy Dec 24 '10 at 9:31
@Ignacio Vazquez-Abrams I was misunderstanding you, you are right of course. x64 is 64 bit but if we are talking about processors that are more exotic than Intel and AMD then 64 bit does not necessarily mean x64. If we are talking Intel and AMD I think my original answer is correct, but I will change it to avoid confusion. – ubiquibacon Dec 24 '10 at 9:34

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