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Help with CPUs

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November 30, 2012 2:07:35 AM

Hey guys, I have been trying to teach myself all about computers and the basics of each individual component and so far so good. But I was looking into all the different CPUs and from what I had learned: i3=2 cores, i5= 4 cores, and i7= 8 cores. Unless they are hyper threaded, in which case they are doubled. However, when I was looking at different intel i7 processors, all of the sites said the i7s had 4 cores..? One had it listed like: # of cores: 4 # of threaded: 8. But I thought they had 8 cores, not 4?
Am I missing something? Im guessing I am just reading something wrong but I would sure like to know. Thanks!

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November 30, 2012 2:25:51 AM

Hi there, I believe the i7's have actually 4 cores but 8 threads. Each core is assigned 2 threads, programs often read it as 8 cores because of the hyper threading.

Edit: Just to specify a bit more, we have 4 physical cores and 8 logical cores. Like I said above each core has 2 threads. So 4x2=8. That's where the 8 comes from. Technically all the games I know don't use hyper threading.
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November 30, 2012 2:29:10 AM

I thought that might be the case. So it would be correct to say: i3=2 cores ( unless hyper threaded which would make it 2 cores which could each handle two threads, so four cores) i5=4 cores and i7=4 cores hyper threaded? If that is the case, then the i5s cant be hyper threaded because that would make them the same as the i7? So in reality an i7 is just a hyper threaded i5? Im sure there are other factors into what makes an i7 different from an i5, but from what Ive read, that statement makes sense to me. Please correct me if Im wrong.
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November 30, 2012 2:31:44 AM

-All i3 have 2 cores, you are correct there.
-MOST i5 have 4 cores but there are a few i5 that only have 2.
-i7 only goes up to 6 cores but most of the are 4 cores.

Im talking about desktop cpus. There are server cpus that go up to 10 cores. What separates the i3, i5, and i7 is the processing power of them. For example as you go up from i3 to i7 the cache they have increases. There are at times when you look at a top end i5 and a low end i7 they are fairly equal same with i3 and i5 but the latter of each one usually has some technology in them that allows them to perform better when needed
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November 30, 2012 2:32:20 AM

Pretty much, the i5's lack hyper threading which the i7's have. The i5 has 1 thread per core. So nothing special there. i7's have 2 threads per core.
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November 30, 2012 2:33:21 AM

i7 has 4 phisical cores and 8 threads in total. The 4 extra threads are created from resource unused by these 4 physical cores, giving more parallelism. i5's have 4 physical cores with no HyperThreading module. i3's have 2 physical cores alltogether 4 threads as i3 has a HyperThreading module as well.

i3 usually ahs turbo boost missing from it's featureset. i5 has turbo boost but has no HTT (hyperthreading technology) and has less 3rd level cache.
i7 has the full featureset.
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November 30, 2012 2:34:30 AM

Damn so many replies, im so slow.
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November 30, 2012 2:36:27 AM

Thanks so much for the answers guys! I understand now
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November 30, 2012 2:37:45 AM

kristjan_i said:
Damn so many replies, im so slow.


Hahaha :lol: 
I myself believe I am slow, usually on easy threads people all jump on it. I have been in many threads to be separated by mere seconds compared to other people's replies.
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November 30, 2012 2:38:35 AM

JarydC33 said:
Thanks so much for the answers guys! I understand now


Basically if you wanna know what HTT is then google it around or if youre to lazy to read, watch videos on intel's website.

All you need to know it it gives more parallelism by using one core as two logical ones and those extra threads are created by unused processing power of the physical cores. Threads aren't useful in menial tasks such as gaming , watching videos, etc.


These come in handy when you're trying to run a virtual machines, trying to edit videos, photos, whatever. Basically the more parallelprocessing you do the more you want an i7

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November 30, 2012 2:40:09 AM

What you read is correct, however, you are misunderstanding what it means.
Basically:
Pentium (G) series = 2 processing cores without Hyperthreading
i3 = 2 processing cores with Hyperthreading enabled = 2cores/4 threads
i5 = 4 processing cores without Hyperthreading = 4 cores/4threads
i7 = 4 processing cores with Hyperthreading enabled = 4 cores/8 threads

Hyperthreading allows each core to load two separate processing threads at a time but only one thread can execute at a time. However, when the first thread per core stalls or finishes the next thead begins to execute immediately until that one finishes or stalls. Having both threads loaded and ready to execute helps improve the speed of the processor by allowing each core to stay busy more often.

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November 30, 2012 12:55:11 PM

Best answer selected by JarydC33.
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