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

[RealEvil]

There is so much misinformation about HT that its starting to p**s me off. Please, everyone who posts some dumbass comment about HT not working in Windows or that you should turn it off or that its no quicker than not having HT PLEASE go and google the subject matter. Type in 'core i7 860 review' into google. Look at the benchmarks for PCs. Read the Wiki Site. Read the Intel site.
In summary... for most apps it wont make any difference (although the bump in clock speed over the i5 750 will give you about 5% more performance), for video ENCODING (not editing) it will give you around a 35% increase. Generally (for average use) thats the advantage you will see. Both Winows 7 and OSX only offload processes to multiple cores when the requesting app really needs it. Most apps dont, so the O/S doesnt use the extra cores. No review of a modern HT processor - especially Lynnfields - recommends you turn it off.

And to everyone who wants to justify their i5 purchase - great. You have a nice processor. Its not as good as the i7 but so what? Enjoy your computer it was cheaper and 'good enough'.

PS This is not about the OP or even necessarily this thread but this forum is full of badly informed people giving their half-assed opinions on the i5/i7 processor options.

 

[andyOSX]

Can people just stop posting this kind of stuff, I don't like it.

@Chundles: thanks.

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.

OMG DID YOU KNOW THE NEW IMAC HAS MAC OS X!!!! OTHER PC COMPUTERS HAVE THIS OTHER OS CALLED WINDOWS!!!!!!

JUST TRYING TO HELP THOSE WHO DIDN'T KNOW!!!!

HT is what makes the i7 different from the i5. An i7 without HT is an i5. Your post is like saying "did you know the Intel iMac has an Intel processor??!!!" Sorry but you can't be that naive, start a whole thread about it and then get all upset when people poke fun at you.

 

[300D]

Andy, they're going to poke a lot more fun at your dumb post than his.

 

[Bryan Bowler]

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.

Mythic,

If you are going to start a thread on HT to help people learn, please do some research first. You have an awful lot to learn about HT and what it can do with today's software platforms.

Bryan

 

[MH01]

OMG DID YOU KNOW THE NEW IMAC HAS MAC OS X!!!! OTHER PC COMPUTERS HAVE THIS OTHER OS CALLED WINDOWS!!!!!!

JUST TRYING TO HELP THOSE WHO DIDN'T KNOW!!!!

HT is what makes the i7 different from the i5. An i7 without HT is an i5. Your post is like saying "did you know the Intel iMac has an Intel processor??!!!" Sorry but you can't be that naive, start a whole thread about it and then get all upset when people poke fun at you.

OMG!!! Unix and Linux no longer run on a PC!!!!!

If you are going to be a smart ass at least get your facts right. HT is not the only diff. I7 also supports triple channel memory. Given that the MB in the imac is not a x58 you are not going to get all the benefits out of an i7.

And in real life usage, the i5 is much better value. And given the the new imacs run i5 P55 MBs, the I5 is the way to go.

Most people have no idea what HT is, so no its not like saying they run intel.

 

[MythicFrost]

OMG DID YOU KNOW THE NEW IMAC HAS MAC OS X!!!! OTHER PC COMPUTERS HAVE THIS OTHER OS CALLED WINDOWS!!!!!!

JUST TRYING TO HELP THOSE WHO DIDN'T KNOW!!!!

HT is what makes the i7 different from the i5. An i7 without HT is an i5. Your post is like saying "did you know the Intel iMac has an Intel processor??!!!" Sorry but you can't be that naive, start a whole thread about it and then get all upset when people poke fun at you.

I'm not naive, yes I get upset when anyone is rude to me about anything. And I'll say it again, your post is rude.
And no it's not, like I said it's not advertised everywhere I barely noticed it, I posted this for those who MAY miss it and miss out on a better deal (or at least what I thought was the better deal and still think is).

Andy, they're going to poke a lot more fun at your dumb post than his.

Although that was saying his is worse, that's still not nice saying mine is dumb because it's not, I was just trying to help those who may have missed it, it's an expensive purchase and I know I'd be furious if I got the i5 instead of the i7 thinking that the i5 had HT.

Mythic,

If you are going to start a thread on HT to help people learn, please do some research first. You have an awful lot to learn about HT and what it can do with today's software platforms.

Bryan

It's not about helping them to learn in the regard I'd have to research anything, only make them aware of one fact and that is the Core i5 does not have HT and the Core i7 does.
I don't know what it can do really, but also don't think I commented anything about what it can do either, I quoted someone saying that it probably won't work in Windows because of the way Apple implemented it, all I said was that I think Windows will just recognize 8 cores just fine - more or less.

 

[ViViDboarder]

Just would like to make a few things clear... HT is not new. It's been around for years and all modern OS support it. You will see performance enhancements with SOME applications of it. If you are running many threads you will see significant enhancements as the OS distributes the load to the 4 physical cores and will see less enhancement as the OS tries to manage extra processes onto virtual cores. As mentioned above, the virtual cores on the same processor cannot access the same part of the processor.

Also, i5 and i7 have been thrown around a lot in the parallel programming world already and most people who know how to take advantage of them know what this means. To the average person just read HT as "a little faster".

Depending on how well the applications are programmed you can see better enhancements with more cores and HT. If you'll notice, when the CoreDuos and first CoreQuads came out there was less performance because developers had to learn how to thread their processes better. Same goes to trying to run processes on 8 virtual cores now.

Also, you forgot to mention that with the use of OpenCL and the dedicated GPU's you can run on even more virtual cores. If you're into learning parallel programming having the extra virtual cores to practice writing larger applications and having a little room to mess around with would be awesome.

I just got the 21.5" though because upgrading my old desktop (mobo, CPU, RAM, GPU, PSU) to an i7 machine is only $600. I'll mess around with that on Koala ... after I finish paying for my iMac.

Anyone else who knows more about computer architecture, feel free (I know you would anyways) to correct some of the finer points of my post.

 

[andyOSX]

If you are going to be a smart ass at least get your facts right. HT is not the only diff. I7 also supports triple channel memory. Given that the MB in the imac is not a x58 you are not going to get all the benefits out of an i7.

Oooh that would cut a lot deeper if you actually knew what you were talking about. We are talking about the iMacs and therefore Lynnfield i7s. Lynnfield i7s support only dual channel memory. You are thinking of Bloomfield, which is not used in the iMac. Thanks for trying though.

"Finally, you have the processor’s integrated DDR3 memory controller, which is cut from three 64-bit channels in Bloomfield to two 64-bit channels with Lynnfield."

In real world tests triple channel memory yields little real world improvement. HT is what makes the i7 valuable.

Maybe you should give this a read: http://www.tomshardware.com/reviews/intel-core-i5,2410-3.html

 

[andyOSX]

I'm not naive, yes I get upset when anyone is rude to me about anything. And I'll say it again, your post is rude.
And no it's not, like I said it's not advertised everywhere I barely noticed it, I posted this for those who MAY miss it and miss out on a better deal (or at least what I thought was the better deal and still think is).

I know I'd be furious if I got the i5 instead of the i7 thinking that the i5 had HT.

It's not about helping them to learn in the regard I'd have to research anything, only make them aware of one fact and that is the Core i5 does not have HT and the Core i7 does.

The reason it's funny is because why would they have a whole different name for it if it was exactly the same? It would just be an upgrade from 2.66 i5 to 2.8 GHz i5. Obviously if there is a different processor involved it would have SOME feature over the other. I think if your post was "What's the difference between i5/i7 no one would have cared. But to come in being like NEWSFLASH: core i5 and i7 are different! - It's just like yea, welcome to yesterday's news...

I don't know why you are so upset about people poking fun at your post. I'm sorry if I upset you but I think part of the reason ppl do it is cuz u are so sensitive about it, it's hard to resist... We don't even know each other...

 

[filmgirl]

There is so much misinformation about HT that its starting to p**s me off. Please, everyone who posts some dumbass comment about HT not working in Windows or that you should turn it off or that its no quicker than not having HT PLEASE go and google the subject matter. Type in 'core i7 860 review' into google. Look at the benchmarks for PCs. Read the Wiki Site. Read the Intel site.
In summary... for most apps it wont make any difference (although the bump in clock speed over the i5 750 will give you about 5% more performance), for video ENCODING (not editing) it will give you around a 35% increase. Generally (for average use) thats the advantage you will see. Both Winows 7 and OSX only offload processes to multiple cores when the requesting app really needs it. Most apps dont, so the O/S doesnt use the extra cores. No review of a modern HT processor - especially Lynnfields - recommends you turn it off.

And to everyone who wants to justify their i5 purchase - great. You have a nice processor. Its not as good as the i7 but so what? Enjoy your computer it was cheaper and 'good enough'.

PS This is not about the OP or even necessarily this thread but this forum is full of badly informed people giving their half-assed opinions on the i5/i7 processor options.

EXACTLY. Yes, the i7 has HT, the i5 does not -- that's the big differentiator. In fact, the new Lynnfield chips, which are designed for the desktop market (and aren't server chips fitted for the desktop like the Bloomfield i7s were), use the P55 chipset and not the X58. Because they use the same chipset, all the i5 really is is a lower-clocked i7 without HT. That's the difference. By disabling HT, Intel can price the chip lower to compete against AMD's Phenom II.

In real world performance differences, like RealEvil says, the difference is largely going to be about clock speed (the 2.8 vs the 2.66) rather than the HT. That isn't to say that in the future as more apps are written to take advantage of HT and virtual cores, that it won't make a difference.

And if you do a lot of virtualization, the HT support will be a big boon. The biggest benefits won't really be visible until more software is written to take advantage of the virtual cores.

And yes, I'm a girl. A girl with a 27" i7 on order. Boo-yah.

 

[wfj5444]

Back to the discussion. The need to turn off HT, was due to a problem with SQL 2000, where HT caused SQL to perform worse. I can't remember if it was SQL 2000 only or also due to an issue with Win2k/2k3.

As far as I remember there isn't a reason to turn off HT now.

 

[Eidorian]

In real world performance differences, like RealEvil says, the difference is largely going to be about clock speed (the 2.8 vs the 2.66) rather than the HT. That isn't to say that in the future as more apps are written to take advantage of HT and virtual cores, that it won't make a difference.

The base clock speed isn't terribly of interest. It's the Turbo bins you get on 1 and 2 cores that factor in as well.

Bloomfield has some depressing Turbo Boost qualities at 130W.

 

[gnasher729]

To the average person just read HT as "a little faster".

A reasonably good approximation to what hyperthreading does: Each hyperthreading core can either act as a single core running at normal speed (100% speed), or two cores running at slower speed (say 60% speed).

If you have a quad core hyperthreading iMac, and you have four different tasks for your computer, it will use four cores at 100% speed, so hyperthreading doesn't give you any advantage. If you have eight tasks, each core will act as two cores running at 60% speed, so you have a total of 8 * 60% = 480% instead of 4 * 100% = 400%. So there is some gain, nothing earth shattering, but still a nice gain.

The "60%" is not fixed, it depends on exactly what code you are running. With some code it could be 50%, with other code it could be 70%.

 

[Compile 'em all]

I'm sensitive, I have my reasons.

Don't use the internet.

 

[filmgirl]

The base clock speed isn't terribly of interest. It's the Turbo bins you get on 1 and 2 cores that factor in as well.

Bloomfield has some depressing Turbo Boost qualities at 130W.

Right you are. I didn't know the Turbo Boost multipliers off-hand, but I know that it's better on the i7 860 than on the i5 750 (though I think even the 750 has better turbo boost handling than the i7 920 bloomfield).

 

[meagain]

Back to the discussion. The need to turn off HT, was due to a problem with SQL 2000, where HT caused SQL to perform worse. I can't remember if it was SQL 2000 only or also due to an issue with Win2k/2k3.

As far as I remember there isn't a reason to turn off HT now.

Thank you!

Could anyone weigh in on the future of HT'ing? Are more apps being developed with/for it increasingly or is it stagnant or ??? And what about games?

I'm not a big gamer but wonder what the difference between i5/i7 would be on say - Spore.

 

[Eidorian]

Right you are. I didn't know the Turbo Boost multipliers off-hand, but I know that it's better on the i7 860 than on the i5 750 (though I think even the 750 has better turbo boost handling than the i7 920 bloomfield).

Clock per clock the architectures are the same for the core and cache components.

I keep dragging this up but the biggest differences are in the platforms they service. There's even this nugget of news for early 2010.

 

[jf8]

Generally (for average use) thats the advantage you will see. Both Winows 7 and OSX only offload processes to multiple cores when the requesting app really needs it. Most apps dont, so the O/S doesnt use the extra cores.

Nonsense. Every SMP OS I've used by default schedules threads/processes on any core without any intervention from the user or process. Applications need not be written in any special way to run on a core other than the first.

It's not "offloading" - from the process's point of view, there's no difference between a process being scheduled in CPU0, 1, 2, or 3. The OS generally treats all cores the same, unless the system is NUMA.

 

[Eidorian]

Nonsense. Every SMP OS I've used by default schedules threads/processes on any core without any intervention from the user or process. Applications need not be written in any special way to run on a core other than the first.

It's not "offloading" - from the process's point of view, there's no difference between a process being scheduled in CPU0, 1, 2, or 3. The OS generally treats all cores the same, unless the system is NUMA.

Thread parking works most of the time under Windows 7. Though I'll admit to forcing CPU affinity on certain single threaded tasks so they load one core at 3.2 GHz instead of bouncing around all the cores at lower speeds.

I don't know of a utility like TMonitor for OS X.

 

[iMacmatician]

Right you are. I didn't know the Turbo Boost multipliers off-hand, but I know that it's better on the i7 860 than on the i5 750 (though I think even the 750 has better turbo boost handling than the i7 920 bloomfield).

CPU          Base     Turbo
                      4 cores  3 cores  2 cores  1 core
Core i7-860  2.80GHz  2.93GHz  2.93GHz  3.33GHz  3.47GHz
Core i5-750  2.67GHz  2.80GHz  2.80GHz  3.20GHz  3.20GHz

 

[300D]

Nonsense. Every SMP OS I've used by default schedules threads/processes on any core without any intervention from the user or process. Applications need not be written in any special way to run on a core other than the first.

Totally correct. OSX makes very good use of multiple cores on its own, it tries to distribute work evenly across all available cores no matter the application or code type.

When one app is only capable utilizing one core, OSX swaps cores every so often to equalize the thermal loading across the CPU. It even puts all the system (red) processes onto the core thats less than 100% to give the other process maximum power.

In the attachment example in AltiVec Power Fractal.app; with multiprocessor code turned on, both cores are utilized 100%. With multiprocessor code turned off, OSX still tries to split the loading as evenly as possible all the time.
=

 

[brasscat]

My 8 core Mac Pro is so fast it boots to yesterday.

 

[MythicFrost]

The reason it's funny is because why would they have a whole different name for it if it was exactly the same? It would just be an upgrade from 2.66 i5 to 2.8 GHz i5. Obviously if there is a different processor involved it would have SOME feature over the other. I think if your post was "What's the difference between i5/i7 no one would have cared. But to come in being like NEWSFLASH: core i5 and i7 are different! - It's just like yea, welcome to yesterday's news...

I knew they were different, but not what makes them different.

I'm sorry if I upset you but I think part of the reason ppl do it is cuz u are so sensitive about it, it's hard to resist... We don't even know each other...

Thx & no worries, and it wouldn't surprise me if that's why people do it lol

Don't use the internet.

Lol, bit hard to do don't ya think? you could also say not to use real life either, or talk to people.

My 8 core Mac Pro is so fast it boots to yesterday.

Lolz, I'd sell it for a hundred million - looks like you got yourself a time machine (pun intended)

 

[53x12]

CPU          Base     Turbo
                      4 cores  3 cores  2 cores  1 core
Core i7-860  2.80GHz  2.93GHz  2.93GHz  3.33GHz  3.47GHz
Core i5-750  2.67GHz  2.80GHz  2.80GHz  3.20GHz  3.20GHz

Thanks for posting this chart. I remember seeing this in an older thread and have been trying to find it ever since.

 

[Maserati7200]

Do you plan on doing some of those tasks simultaneously?

I've never attempted that (my Mid 2007 MB cannot handle that), but it would be nice if I could. So yeah, I would rather be able to do some of those simultaneously.