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Intel is dropping hyperthreading from i7 chips!

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Feb 27, 2014
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If all rumors are true, AMD could have on the next generation:

- Epyc 64c128t
- TR 32c64t
- R7 16c32t
- R5 12c24t and 8c16t
- R3 8c8t

In this case, those i7 would have the same configuration as Ryzen 3, but they would probably be faster.
 

IntelUser2000

Elite Member
Oct 14, 2003
7,250
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No, 8/6= 1.33.

This makes the 8C/8T part 33% faster than 6c/6t on parallel applications.
You sound like my former classmates that said dual cores are like having 2x clocked single cores. :rolleyes:

I'm pretty sure you know more than you let on.

https://www.hardware.fr/articles/970-5/coffee-lake-kaby-lake-ryzen-3-5-ghz.html
https://www.hardware.fr/articles/956-7/impact-smt-ht.html

Zen SMT off vs SMT on is actually quite comparable to 6 core vs 8 core Zen. In memory bound applications like 7-Zip and WinRAR, the additional ability of SMT to hide memory misses allow SMT to do even better than having 33% extra cores. In fact, for those two applications, their tests are showing for Intel chips, HT might be better than having 50% extra cores. No application shows 50% gain for having 50% more cores either. That's what I meant by real world not having linear scaling.

one or two niche applications that happen to suit HT very well.
The same applications that benefit from many threads benefit from having HT. That's why a 2C CPU gained huge amounts even on games by having HT enabled, while there was nothing on 4 cores.

I do believe 8C/8T will be 5-10% better in certain applications(definitely games), but you are certainly the master of exaggeration when you say benefits from HT are seen in one or two niche applications.
 
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AtenRa

Lifer
Feb 2, 2009
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8C 8T at same TDP could possible sustain turbo for more time than having 6Cores + HT simple because 8Core SKUs will not use all Core resources. So each Core will not increase temperatures as fast as cores with HT enabled. But if you have a large Heat-sink or using water it will not make a difference.

Generally it will be a side grade going from 6C 12T to 8C 8T on the same architecture and same clocks.
 

happy medium

Lifer
Jun 8, 2003
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Is there something im missing?
Why is important to know which CPU is faster, 6 core 12 threads vs 8 core 8 threads?
Thanks.
 

coercitiv

Diamond Member
Jan 24, 2014
4,111
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Is there something im missing?
Why is important to know which CPU is faster, 6 core 12 threads vs 8 core 8 threads?
Thanks.
Because 9700K is the successor of the 8700K. You know, we kinda got used to new gen being upgrades.
 

happy medium

Lifer
Jun 8, 2003
14,387
471
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Because 9700K is the successor of the 8700K. You know, we kinda got used to new gen being upgrades.
If you were gonna upgrade wouldnt the 8 core , 16 thread chip be your new upgrade? I thought that would be a simple answer.

Are you saying the names of the chips are confusing?
 

happy medium

Lifer
Jun 8, 2003
14,387
471
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No mate, I'm saying the prices are confusing.
Oh ok I see.
So the 9700k will cost more than the 8700k and give the same base performance, overclock the same, and use the same power envelope as the 8700?
So the 9700k will cost more than $ 380? That was the 8700k price a few months back on newegg.

I missed that news.
Thanks
 

PeterScott

Platinum Member
Jul 7, 2017
2,605
1,540
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You sound like my former classmates that said dual cores are like having 2x clocked single cores. :rolleyes:
Actually one of my CS profs said something to that effect. Something along the lines of: if you could choose between a single CPU with X resources (cache) and X speed, it was always the better choice than Y CPUs with X/Y resources and X/Y speed. Because you can always subdivide your resources of the powerful entity and do it more efficiently, than you can combine the lessers.

I do believe 8C/8T will be 5-10% better in certain applications(definitely games), but you are certainly the master of exaggeration when you say benefits from HT are seen in one or two niche applications.
I think you misread what I wrote. I didn't say that HT only offers benefits in one or two niche applications. I said that Intel 6/12 would best 8/8, only in one or two niche applications.

Of your list, really only 7-zip really qualifies as winning that fight IMO. Time will tell.
 
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TheELF

Diamond Member
Dec 22, 2012
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That a core has 100% load does not mean there is never a momentary stall in the pipeline because of memory requests or instructions needing result from previous instructions. The execution units are idle at those moments and that is when HT or SMT is convenient.
This is called switch on event multithreading and has been around since the amiga OS 1 for desktop.
It has absolutely nothing to do with HTT/SMT and happens on single cores.
 
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PingSpike

Lifer
Feb 25, 2004
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For half a decade Intel sold i3 2c4t and a i5 4c4t. Pretty much nobody cawed about how the i3 was better than the i5 because it had hyperthreading. Coffeelake came out. i5s went to 6 cores, i3 LOST hyperthreading and went to 4 cores. Never heard anybody say that was bad.

Now, all of sudden an i7 has more cores and no HT and its a big deal for some reason.

I guess the only way to make everyone happy would have been a new i9 8c8t AND a new i11 8c16t. You know, except for all the mobile and low power offerings which will continue to toss the conventions out the window. And obviously HEDT is its own thing it the iX business.
 

PingSpike

Lifer
Feb 25, 2004
21,328
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When Core i3 was dual core + HD the Core i5 had double the Cores but equal threads
If we take Core i7 8700K as a new Core i3 then the new Core i5 would be a 12Core 12T CPU

;)
LOL, I guess you're right. I guess we'll have to bench for waitmarks to see.
 
May 11, 2008
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This is called switch on event multithreading and has been around since the amiga OS 1 for desktop.
It has absolutely nothing to do with HTT/SMT and happens on single cores.
You invent things. The 68000 was a very advanced cpu at the time but it did not have SMT /HT and the 68000 was certainly not a superscalar core.

HT /SMT can work because a super scalar out of order core has multiple execution units running in parallel that sometimes need to wait(idle/ stalled, whatever you want to call it) for either memory access, or are waiting for instruction depencies to be resolved. Because of this waiting, there is in HT/ SMT capable cores time to run another thread. When there is ideal code written that never causes an execution unit to wait in the pipeline, only then does HT or SMT nothing or can even cause performance degradation in some rare cases. Most existing code is not written optimal or the nature of the code does not allow for a superscalar cpu core to use all its resources in parallel, hence HT /SMT works.
 
May 11, 2008
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The first generation ones yeah.
Indeed. I wonder if that is because it was an in-order core and that there was much less benefit than with an out of order core.
The atoms are also superscalar. And the latest atoms are out of order super scalar cores. I just read for servers. Perhaps because hyperthreading can pose a security risk (was so with the pentium 4) and the cores are so small that it is easy to just put a lot of them parallel and forget about hyperthreading ?
 

moonbogg

Diamond Member
Jan 8, 2011
9,904
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Intel is going to look pretty silly when they are forced to bring back HT to fight a 7nm AMD. If the removal of HT from the i7 is true, then its a mistake IMO. If they are simply renaming all their i7's as i9's, that's also a huge mistake IMO. Why destroy your own brand like that? No brand is stronger than the i7, and trying to condition people to now consider the i7 as "second best" could backfire. Its confusing and kind of funny to watch actually. Big bad 8 core i7 without HT, LOL! That's funny right there.
16/32 7nm cannons about to direct their fire on Intel in the mainstream, at high clocks too...now THAT will be funny.
 
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jpiniero

Diamond Member
Oct 1, 2010
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Intel is going to look pretty silly when they are forced to bring back HT to fight a 7nm AMD. If the removal of HT from the i7 is true, then its a mistake IMO. If they are simply renaming all their i7's as i9's, that's also a huge mistake IMO. Why destroy your own brand like that?
Because they want to charge $450, and that's not the i7 price bracket range.
 
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epsilon84

Senior member
Aug 29, 2010
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Intel is going to look pretty silly when they are forced to bring back HT to fight a 7nm AMD. If the removal of HT from the i7 is true, then its a mistake IMO. If they are simply renaming all their i7's as i9's, that's also a huge mistake IMO. Why destroy your own brand like that? No brand is stronger than the i7, and trying to condition people to now consider the i7 as "second best" could backfire. Its confusing and kind of funny to watch actually. Big bad 8 core i7 without HT, LOL! That's funny right there.
16/32 7nm cannons about to direct their fire on Intel in the mainstream, at high clocks too...now THAT will be funny.
No one except enthusiast geeks cares about HT. Even my friends who are into gaming just assume i7 is 'better' because of the higher number, not because it has HT.

In a practical sense, i9 works if its the only SKUs that have HT. Intel also wants to charge more for the 8/16 chip, as jpineiro said, and $450 for a 'not so premium' i7 is probably a tough sell. For an i9? They can probably get away with it.

From a marketing perspective, this doesn't hurt Intel. From a competitive standpoint? Well, certainly a 9700K will lose some benchmarks to a 2700X but it will win some as well, so if its priced around $350 then its 'about right', especially considering the reported 4.6GHz-4.9GHz out of the box clockspeeds.

As far as 16c/32t on desktop goes, I'm struggling to see how a 16/32 chip would be beneficial to your typical desktop machine apart from niche cases. This 'moar cores' war is getting silly, I would honestly prefer a jump in IPC and clockspeeds from AMD, even if they remain at 8/16, rather than a doubling of cores ever 24 months at the cost of lower overall frequencies.
 

TheELF

Diamond Member
Dec 22, 2012
3,163
357
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You invent things. The 68000 was a very advanced cpu at the time but it did not have SMT /HT and the 68000 was certainly not a superscalar core.

HT /SMT can work because a super scalar out of order core has multiple execution units running in parallel that sometimes need to wait(idle/ stalled, whatever you want to call it) for either memory access, or are waiting for instruction depencies to be resolved. Because of this waiting, there is in HT/ SMT capable cores time to run another thread.
This (doing stuff while) waiting is called switch on event and has nothing to do HTT/SMT it's a completely different thing that does not need any special kind of CPU(core).
Read the article in the link and look up the CPUs it says implement this technique...

When there is ideal code written that never causes an execution unit to wait in the pipeline, only then does HT or SMT nothing or can even cause performance degradation in some rare cases.
No it also has to use every execution unit the core has available because HTT uses the idle units.
There is zero app today that can use all available execution units of today's CPU cores,in fact it's been a lot of years where unit number in CPUs increase while software keeps running at the same speed.
 

TheELF

Diamond Member
Dec 22, 2012
3,163
357
126
Intel is going to look pretty silly when they are forced to bring back HT to fight a 7nm AMD. If the removal of HT from the i7 is true, then its a mistake IMO. If they are simply renaming all their i7's as i9's, that's also a huge mistake IMO. Why destroy your own brand like that? No brand is stronger than the i7, and trying to condition people to now consider the i7 as "second best" could backfire. Its confusing and kind of funny to watch actually. Big bad 8 core i7 without HT, LOL! That's funny right there.
16/32 7nm cannons about to direct their fire on Intel in the mainstream, at high clocks too...now THAT will be funny.
Once upon a time the i5 for desktop was 2 cores +HTT today i3 has 4 cores, times change and intel creates SKUs that fits their agenda, if it makes sense to them to sell it without HTT so it's not too overpowered against the lower tier (so that they still be able to sell the lower tier as well) then that's what they will do.
 
May 11, 2008
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This (doing stuff while) waiting is called switch on event and has nothing to do HTT/SMT it's a completely different thing that does not need any special kind of CPU(core).
Read the article in the link and look up the CPUs it says implement this technique...


No it also has to use every execution unit the core has available because HTT uses the idle units.
There is zero app today that can use all available execution units of today's CPU cores,in fact it's been a lot of years where unit number in CPUs increase while software keeps running at the same speed.
Sigh..
Switch on event is also known as coarse grain multithreading and has nothing to do with hyperthreading or simultaneous multithreading.
There is also fine grain mutlthreading where multiple instructions are executed in parallel but all are from the same thread each cycle.
Switch on event means that when a thread stalls, another threads gets to run.
This is handled by the kernel.
This has nothing to do with HT or SMT which is happening on the cpu itself which has to be super scalar and where actually instructions from totally different threads can run simultaneously.
With Zen and almost all Intel CPUs since the pentium 4, there are resources to run the instructions of two totally different threads on a single core.

I already explained how it works.


edit:
Here is a wiki :
https://en.wikipedia.org/wiki/Superscalar_processor

A superscalar processor is a CPU that implements a form of parallelism called instruction-level parallelism within a single processor. In contrast to a scalar processor that can execute at most one single instruction per clock cycle, a superscalar processor can execute more than one instruction during a clock cycle by simultaneously dispatching multiple instructions to different execution units on the processor. It therefore allows for more throughput (the number of instructions that can be executed in a unit of time) than would otherwise be possible at a given clock rate. Each execution unit is not a separate processor (or a core if the processor is a multi-core processor), but an execution resource within a single CPU such as an arithmetic logic unit.
 
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May 11, 2008
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While reading up about instruction level parallelism makes me wonder if HT enabled limits the ability to run the cpu at higher clocks.
Because all the logic circuitry to check and keep track of which instructions are in flight and check which instruction belongs to which thread has to be able to clocked high as well and may limit the maximum clock. If that is true, it makes sense that Intel comes up with the ultimate overclockable cpu for games. A cpu that does not have HT enabled. And since there are enough cores, there is no real limitation with 8C/8T cpus. That idea, should be easily tested by taking a 8700K and see if it clocks higher with HT disabled in comparison to HT enabled.
Anybody willing to test it ?
 

slashy16

Member
Mar 24, 2017
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I rather have an 8C/8T cpu that runs at a higher sustained turbo than a 8C/16T CPU which has to throttle itself a few minutes. I think Intel's new marketing i3(budget), i5(budget gamer), i7(extreme gamer), i9 (Extreme Gamer & Pro) works well. They are competitive in all areas right now. enabling HT across the board can be reserved for next year as a marketing ploy as a stop-gap if their 10nm is delayed again. The benchmarks and work loads where HT shows a healthy boost are not where Intel is targetting their i3/i5/i7.
If you need HT or care about HT, intel rather you buy a i9 or XeonW.

Intel has sold HT in the past as a feature you can unlock with a key you can purchase from a website. I wonder if we will see that go mainstream.

I bought a 2700x recently and I was able to hit 4.1ghz all cores with SMT enabled. I disabled SMT and was able to get 4.3ghz stable. I also noticed games run better without SMT enabled especially older games which only use 1-2 threads. Needless to say, SMT is now permanently disabled.
 
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