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The i5 doesn't have Hyper-threading and only has 4 cores, i7 does and has 8

MythicFrost

MythicFrost

macrumors 68040
Original poster
Mar 11, 2009
3,944
40
Australia
I just realized I think it was early this morning that the i5 iMac does not have hyper threading, so it's just a quad core, the i7 is a quad core but has HT so OSX recognizes eight cores.

Did anyone actually know this? I thought I'd post this just in case some people didn't.
 
It's not that hard to read all this off of Apple's own iMac specification page.

Apple.com said:
27-inch models only, one of the following:

* 2.66GHz quad-core Intel Core i5 processor with 8MB shared L3 cache; Turbo Boost dynamic performance up to 3.2GHz
* 2.8GHz quad-core Intel Core i7 processor with 8MB shared L3 cache; Turbo Boost dynamic performance up to 3.46GHz; Hyper-Threading for up to eight virtual cores
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MythicFrost said:
I just realized I think it was early this morning that the i5 iMac does not have hyper threading, so it's just a quad core, the i7 is a quad core but has HT so OSX recognizes eight cores.

Did anyone actually know this? I thought I'd post this just in case some people didn't.
Click to expand...

Thanks for the insight Sherlock.
 
MythicFrost said:
I just realized I think it was early this morning that the i5 iMac does not have hyper threading, so it's just a quad core, the i7 is a quad core but has HT so OSX recognizes eight cores.

Did anyone actually know this? I thought I'd post this just in case some people didn't.
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If it recognizes 8-cores why is it considered as a quad core?
 
ronaldcastillo said:
If it recognizes 8-cores why is it considered as a quad core?
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Because it is a quad core machine. It has four physical processing cores. Each of these cores however can do two things at once (to put it simply) so the processor shows as having 8 logical cores.
 
Wow, there's no need to be rude I was just trying to help anyone who didn't know.
It's not that hard to read all this off of Apple's own iMac specification page.
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I don't know if that was meant to be rude or not but it came across that way, and yes I know I read it there after someone told me the i5 didn't have HT, until then I didn't have a clue.
Thanks for the insight Sherlock.
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That's just rude.

I was just trying to help...
 
Maserati7200 said:
Question: would I notice the difference on an iMac? I usually have 5-12 apps open at once, I edit 720p video (may edit 1080p in the future), use garageband, iphoto, and handbrake. Would there be a significant difference between an i5 and i7 in those areas?
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Do you plan on doing some of those tasks simultaneously?
 
Mythic - While I did know the answer to your title post, it took me a while to get there by digging around. I know your post will be helpful to many.

I've opted for the i7 mostly for dealing with HD video. What a PITA that is. I hope to be able to multi-task while processing it, etc. The benchmarks I've read imply the i7 will help greatly so I'm rolling with that. I figure for $200 over 3 years? of ownership, if that saves me time, allows me to do tasks simultaneously, etc. - then it's worth it to me big time.

One thing that bothers me is that I've read a few blurbs where pro-audio people (studio type situations) turn off hyperthreading. I have no idea how old those posts were and I don't think they were macs - but it sort of concerned me. I wonder why? I also wonder if it's possible to shut it off on our Macs if warranted.
 
I know your post will be helpful to many.
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Thank you, as intended :)
What a PITA that is.
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What's a PITA?
One thing that bothers me is that I've read a few blurbs where pro-audio people (studio type situations) turn off hyperthreading. I have no idea how old those posts were and I don't think they were macs - but it sort of concerned me. I wonder why? I also wonder if it's possible to shut it off on our Macs if warranted.
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I believe Pro Tools had a problem with the hyper-threading on the Nehalem Mac Pro, I don't remember what but I think it was pretty bad, I think it's been fixed but I don't know.
I'm not sure about any audio production tools/software. It probably is possible to turn the HT off.
Can anyone clarify on this?
 
MythicFrost said:
I just realized I think it was early this morning that the i5 iMac does not have hyper threading, so it's just a quad core, the i7 is a quad core but has HT so OSX recognizes eight cores.

Did anyone actually know this? I thought I'd post this just in case some people didn't.
Click to expand...

2007-07-17-captainobvious.jpg
 
MythicFrost,

Ok, here's the deal. Some of us are giving you a hard time because you are posting something that been discussed over and over since the iMac has been released. If you took some time to look around, you find no less than 15 or 20 threads that discuss this issue.

It's akin to getting on and saying, "I just realized that the new iMacs have bigger screens. I thought I'd post this in case you didn't know."

Bryan
 
mgzilla said:
2007-07-17-captainobvious.jpg
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Lolz nice one noobs!
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Can people just stop posting this kind of stuff, I don't like it.

@Chundles: thanks.
MythicFrost,

Ok, here's the deal. Some of us are giving you a hard time because you are posting something that been discussed over and over since the iMac has been released. If you took some time to look around, you find no less than 15 or 20 threads that discuss this issue.

It's akin to getting on and saying, "I just realized that the new iMacs have bigger screens. I thought I'd post this in case you didn't know."

Bryan
Click to expand...
Yes it's probably been discussed in the context of large threads, this was a thread purely about this, for those who don't read through incredibly large posts and may miss it.
It's obvious the iMacs have bigger screens, it's advertised everywhere however "Core i5 does not have HT" is not advertised everywhere, I've read the spec page for the iMac about 5 times if not more, and missed it every time.

And in the case that someone did post the new iMacs have bigger screens, I would have either not replied if I knew and say thanks if I didn't.
I posted this just to help anyone who didn't know, that's why the title said what it said to attract those who didn't know, compared to "I just realized the i5 didn't have HT".

Considering this was serious and only intended to help anyone who may have missed this little bit of info like I did, I don't understand why I get harsh posts, if it really bothers you that I posted it then it would seem logical to not post and ignore it.
 
For audio editing the i5 would do you plenty good. But if you plan on editing 1080p, I'm more than certain the graphic card in the high end iMac won't cut it too well. If I were you, I would wait until the new Mac Pros are released and get a previous gen Mac Pro with a higher end video card in it, this will give you better performance imo.

I'm not due to upgrade my computer for one more year (mid August to mid November every two years), but I'm really considering a Mac Pro over an iMac (especially since I plan on keeping my current iMac instead of selling it off). I want to do editing in 1080p as well as get into some cool multimedia projects that are fairly graphic intensive. And with the audio I'm working with, I need a much better audio card than a one output port on the iMac. The current generation of the Mac Pro, with just four cores, mid range ghz, higher end graphics, and 8 to 12 gigs of ram should do me just fine. Of course by the time I buy the newer Mac Pros will have already been out.

And I didn't know they had double virtual cores, which is good but I could only imagine as good as Apple implements it. I don't think it will work at all on the Windows side.
 
Rapmastac1 said:
For audio editing the i5 would do you plenty good. But if you plan on editing 1080p, I'm more than certain the graphic card in the high end iMac won't cut it too well.
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Please elaborate.

Rapmastac1 said:
I'm not due to upgrade my computer for one more year (mid August to mid November every two years), but I'm really considering a Mac Pro over an iMac (especially since I plan on keeping my current iMac instead of selling it off). I want to do editing in 1080p as well as get into some cool multimedia projects that are fairly graphic intensive. And with the audio I'm working with, I need a much better audio card than a one output port on the iMac. The current generation of the Mac Pro, with just four cores, mid range ghz, higher end graphics, and 8 to 12 gigs of ram should do me just fine. Of course by the time I buy the newer Mac Pros will have already been out.
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I'd definitely wait for next year's Mac Pro. The expansion capability is nice on the Early 2009 model but the raw computing hardware is lackluster.

Rapmastac1 said:
I don't think it will work at all on the Windows side.
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Please elaborate.
 
MythicFrost said:
Can people just stop posting this kind of stuff, I don't like it.
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Mythic, I'm sorry, but this is an open discussion board and discussions take place. If you don't like what someone says, then thicken up and don't let it get to you. My sarcastic remark was not meant to hurt your feelings, so I am sorry for that.

Bryan
 
My sarcastic remark was not meant to hurt your feelings, so I am sorry for that.
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Thank you, and apology accepted (I appreciate it) :)
Mythic, I'm sorry, but this is an open discussion board and discussions take place.
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Yeah, all I can do is bring it to someone's intention if they upset me.
If you don't like what someone says, then thicken up and don't let it get to you.
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I'm sensitive, I have my reasons.

And I didn't know they had double virtual cores, which is good but I could only imagine as good as Apple implements it. I don't think it will work at all on the Windows side.
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If you are referring to the Core i7 having an additional 4 virtual cores, the OS just recognizes 8 cores, if Windows couldn't make use of them then you wouldn't see them around as much I don't think.
 
It has 8 logical cores, but two threads cannot try to use the same part of the processor at once.

If you have 8 processes and 6 of them need the same specific function of a core, 2 processes are going to have to wait and share with the others.
 
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