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How is it that multi-core processors work?

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July 6, 2007 5:48:03 AM

Is it that each core runs at the clockspeed provided (like on the Q6600, does each core run at 2.4ghz) or is it that each core runs at 1/4 of that speed? Another example is the Core 2 Duo E6850. Does each core run at 3.0ghz or do the cores working together equal 3.0ghz? If a game like say, CS:S is only single threaded, do you get one core working at 1.5ghz on the game or do you get one core working at 3.0ghz? thanks
July 6, 2007 6:01:16 AM

Eg. Q6600. 4x 2.4ghz In single threaded application, you can only use one of the 2.4ghz core at the most. While in multithreaded, the program can use all 4 of the 2.4ghz cores at the same times thus effectively quadruplying the processing power. Think of quad core 2.4ghz as 4x2.4ghz four cores all operating at 2.4ghz not 9.6ghz in total nor 600mhz for each cores.
July 6, 2007 7:23:26 AM

How do you explain this picture then: http://img388.imageshack.us/my.php?image=core2ne7.jpg

He has a 1.7ghz dual core, and it says his processor is 2x86 and if you do the math (2x860) it gives you 1720mhz... also, when he runs shadowrun which is a dual threaded game, he clocks in at like 860mhz on each core. why is this?
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July 6, 2007 7:40:42 AM

2x86 means two x86 class processors and not two x64 processors (which probably has more to do with the fact that he is running Vista x86 than anything else.

That has nothing to do with the speed of the PC.
July 6, 2007 7:35:32 PM

Have you heard of processors called X386 or x386/64? X386 is 32bit processor that you can buy from AMD and Intel right now and the X386/64 are 64bit processor that you can buy from intel. 2x86 is not 2 times 86, its 2 times x86s.
July 6, 2007 11:56:35 PM

Quote:
How do you explain this picture then: http://img388.imageshack.us/my.php?image=core2ne7.jpg

He has a 1.7ghz dual core, and it says his processor is 2x86 and if you do the math (2x860) it gives you 1720mhz... also, when he runs shadowrun which is a dual threaded game, he clocks in at like 860mhz on each core. why is this?


2 x 86 = 172.
July 7, 2007 8:18:50 AM

Quote:
Have you heard of processors called X386 or x386/64? X386 is 32bit processor that you can buy from AMD and Intel right now and the X386/64 are 64bit processor that you can buy from intel. 2x86 is not 2 times 86, its 2 times x86s.


:roll: Both AMD and intel make 64 bit processors
July 7, 2007 8:47:39 AM

A multi core processor is nothing more than putting more cpus into one package.

if a multicore cpu is rated at 2.4 GHz, every single core runs at 2.4 GHz.

If a game or app is multithreaded, it will be able to use more than one of those cores at a time.

Do not assume that the clockspeed of a quad core 2.4 GHz cpu is 4 x 2.4 GHz (9.6 GHz). Its just 2.4 GHz.

The cores in a multi core cpu cant magically share the load if a program is not multi threaded. they have to be explicitly told to do work, there is no such thing as reverse hyperthreading.

Windows itself will use lots and lots of threads, so even if a game isnt multi threaded, windows will be able to use the extra cores.

x86 is an architecture basically invented by Intel about 20 years ago. It has been evolving since then. x64, or x86-64, is the x86 architecture with 64 bit extensions. both amd and intel make 64 bit cpus.
July 7, 2007 9:26:59 AM

What you can do is set the affinity to do certian tasks, say you want to game but use a virus scan at the same time, make the virus scanner say work on core 2 or 3. Its really useful.
July 7, 2007 2:49:51 PM

I dont actually do it, its just an example of the things that mutli cores can do :D 

A single core would struggle with that.
July 7, 2007 4:10:01 PM

Lol i know it will confuse the issue but actually intel are considering such a system. Laptop chips are limited by power and thermal considerations rather than the maximum speed of the silicon. It is planned that some chips will raise the clock of one of the cores when presented with a single threaded load.
July 7, 2007 4:11:25 PM

Turpit wrote:
Quote:
jackluo923 wrote:
Have you heard of processors called X386 or x386/64? X386 is 32bit processor that you can buy from AMD and Intel right now and the X386/64 are 64bit processor that you can buy from intel. 2x86 is not 2 times 86, its 2 times x86s.


Rolling Eyes Both AMD and intel make 64 bit processors


Thats what i said
Quote:
you can buy from AMD and Intel
July 7, 2007 5:33:10 PM

Quote:
Turpit wrote:
jackluo923 wrote:
Have you heard of processors called X386 or x386/64? X386 is 32bit processor that you can buy from AMD and Intel right now and the X386/64 are 64bit processor that you can buy from intel. 2x86 is not 2 times 86, its 2 times x86s.


Rolling Eyes Both AMD and intel make 64 bit processors


Thats what i said
Quote:
you can buy from AMD and Intel


No, you said this. Exactly:

Quote:
Have you heard of processors called X386 or x386/64? X386 is 32bit processor that you can buy from AMD and Intel right now and the X386/64 are 64bit processor that you can buy from intel. 2x86 is not 2 times 86, its 2 times x86s
July 9, 2007 5:49:59 PM

hey guys i originally asked this question for a friend that said if you have a 2.4ghz than each core runs at 1.2ghz which i thought was wrong. but now i have another question. if you had a quad-threaded program and you ran it with a Q6600 would you technically be running it at 9.6ghz since each core is synchronized?
July 9, 2007 6:45:34 PM

sh4d0wblade said:
hey guys i originally asked this question for a friend that said if you have a 2.4ghz than each core runs at 1.2ghz which i thought was wrong. but now i have another question. if you had a quad-threaded program and you ran it with a Q6600 would you technically be running it at 9.6ghz since each core is synchronized?



Nope, its still only running at 2.4 GHz, but it would run 3.x times faster than on a single core. Your not multiplying the actual speed at which the work is being done, just the amount of work being done.

Remember the old word problems in grade school math? 'If bob and his 3 brothers can each paint 1 house in 8 hours by themselves, how long could they paint 1 house if the worked together? Answer = 2hrs. Think of it that way; none of the cores are working faster, they are just working together on different parts of the same problem.


In a single threaded app, the other 3 cores act like supervisors on a state road crew....they all stand around doing nothing ;) 
!