Is HyperThreading/SMT really needed?

[whm1974]

When I built my current rig back in 2013 I could have chosen an Haswell i7 instead of the i5 I pick and now I'm wondering if I should have given that I will not be building a new rig anytime soon.

What about now when building a new system, does it matter? And Yes I know we must also factor in cost as well. But what are you guys thoughts about this?

 

[Paratus]

When I built my current rig back in 2013 I could have chosen an Haswell i7 instead of the i5 I pick and now I'm wondering if I should have given that I will not be building a new rig anytime soon.

What about now when building a new system, does it matter? And Yes I know we must also factor in cost as well. But what are you guys thoughts about this?

With my 1900X 8 core 16 threads Threadripper CPU in Cinebench R15 I get a single core score around 168 and a multi core score around 1750.

That works out to a 10.5 multiplier.

So SMT is giving me about 30% more performance or the equivalent of another 2.5 real cores. It’s been worth it to me.

 

[whm1974]

With my 1900X 8 core 16 threads Threadripper CPU in Cinebench R15 I get a single core score around 168 and a multi core score around 1750.

That works out to a 10.5 multiplier.

So SMT is giving me about 30% more performance or the equivalent of another 2.5 real cores. It’s been worth it to me.

Thanks, something to keep in mind next time I build. Of course by then maybe SMT will be a standard feature on all CPUs.

 

[tential]

The i5 is only a good processor in canned gaming benchmarks. You want the i7
I mean, unless you always run your system as a fresh install of windows, you want some extra threads available to you, and thats the i7. The i5 is running your system barebones.

 

[whm1974]

The i5 is only a good processor in canned gaming benchmarks. You want the i7
I mean, unless you always run your system as a fresh install of windows, you want some extra threads available to you, and thats the i7. The i5 is running your system barebones.

Well I use Linux, but I'm saving my money up for a new build in a few years.

 

[TheELF]

The i5 is only a good processor in canned gaming benchmarks. You want the i7
I mean, unless you always run your system as a fresh install of windows, you want some extra threads available to you, and thats the i7. The i5 is running your system barebones.

Do you even have any idea about how many threads even a fresh install of windows runs on a clean boot?Go read a book about how operating systems work.

Sure console games are sometimes incredibly badly coded and lock up your system because they are made for a non multithtreading environment but vsync or just a weak gpu takes care of that,you don't have to waste your money on more cores/threads.

 

[LTC8K6]

Well I use Linux, but I'm saving my money up for a new build in a few years.

In a few years the entire CPU landscape will be different.

In the meantime, your i5 is enough for anything you might choose to do, and you did not make any big error by not going with an i7.

By waiting, you have missed a lot of pains in the ass, actually.

 

[whm1974]

In a few years the entire CPU landscape will be different.

In the meantime, your i5 is enough for anything you might choose to do, and you did not make any big error by not going with an i7.

By waiting, you have missed a lot of pains in the ass, actually.

Thanks, that nice to know. Of the two main reasons I'm waiting is I don't have the money to build a nice rig and two, my current setup is good enough not to even if I did have the money.

 

[Spjut]

The new i5s are six core CPUs, so it's alot harder to motivate the i7 based on today's games. When comparing older i7 CPUs to i5 though, the i7 have aged alot better.

 

[Thunder 57]

The new i5s are six core CPUs, so it's alot harder to motivate the i7 based on today's games. When comparing older i7 CPUs to i5 though, the i7 have aged alot better.

Very true. A quick look at i5 vs i7 pricing on ebay would verify that. Hyperthreading matters a good bit more than it did back in 2013. I made the same call in early 2013 and went with an i5. These days, I'd probably go for an i7.

 

[whm1974]

Very true. A quick look at i5 vs i7 pricing on ebay would verify that. Hyperthreading matters a good bit more than it did back in 2013. I made the same call in early 2013 and went with an i5. These days, I'd probably go for an i7.

Well my case I'll probably go with an 8c/16t CPU when I get around to building a new rig.

 

[tential]

The new i5s are six core CPUs, so it's alot harder to motivate the i7 based on today's games. When comparing older i7 CPUs to i5 though, the i7 have aged alot better.

Yes, because we only play todays games. /s
That's why I despise the i5.
Because it leads to extremely shortsighted thinking.
Spend the small extra money and get the i7 for the longevity.

@whm1974
That's the right call.
the 9700k is your best bet.
If you can't afford it, get the AMD equivalent.

Do NOT limit yourself thread/core wise. It just is short sighted.

 

[Thunder 57]

Yes, because we only play todays games. /s
That's why I despise the i5.
Because it leads to extremely shortsighted thinking.
Spend the small extra money and get the i7 for the longevity.

@whm1974
That's the right call.
the 9700k is your best bet.
If you can't afford it, get the AMD equivalent.

Do NOT limit yourself thread/core wise. It just is short sighted.

Why would you despise a product? You don't have to buy it, and it is filling the gap between the i3 and i7. It's obviously not as efficient as an i7 because of the lack of HT and a smaller L3, but it's a solid upgrade over the i3. I don't see how choice is a bad thing.

 

[DrMrLordX]

Why would you despise a product?

You don't know what that i5 did to him behind closed doors.

You

Don't

Know

 

[PeterScott]

With my 1900X 8 core 16 threads Threadripper CPU in Cinebench R15 I get a single core score around 168 and a multi core score around 1750.

That works out to a 10.5 multiplier.

So SMT is giving me about 30% more performance or the equivalent of another 2.5 real cores. It’s been worth it to me.

Which is great if your main usage is running a synthetic benchmark.

Now how about how it impacts what you actually use your PC for?

 

[ehume]

. . . the 9700k is your best bet. . . .

If OP is waiting, perhaps waiting another 2-3 generations is more in order bedause of the recently-discovered problems found with speculative execution affecting CPU's from Intel, AMD and ARM. OP, you seem to be able to wait, so wait until Intel and AMD have fixed their hardware.

 

[Paratus]

Which is great if your main usage is running a synthetic benchmark.

Now how about how it impacts what you actually use your PC for?

My first rig was a P4 Prescott eek. Thanks to the extra thread from HT it remained a fairly smooth experience for 5 years, even if a program was thrashing away in the background.

My i7920 and it’s 4C/8T were all used during video encoding which I do a bit of. Plus my entire family uses that machine. It remained responsive even when others were leaving crap running in the background.

Now I expect the new TR to be even faster at encoding and remain responsive regardless what we throw at over the next couple of years. I’d also expect that software becomes more multithreaded aware now that intel has finally started adding more cores.

(Quite frankly I was very disappointed that when I started looking at a new machine last year intel mainstream was the same 4C/8T I have had since 2010, just with fewer dim slots and PCIe lanes - what the hell have they been doing for 7 years?)

Now if you are the only user, only play games and want to rebuild the machine every couple of years another cheap quad core might make sense. Anything else, I’d recommend getting more threads.

 

[PeterScott]

My first rig was a P4 Prescott eek. Thanks to the extra thread from HT it remained a fairly smooth experience for 5 years, even if a program was thrashing away in the background.

My i7920 and it’s 4C/8T were all used during video encoding which I do a bit of. Plus my entire family uses that machine. It remained responsive even when others were leaving crap running in the background.

Now I expect the new TR to be even faster at encoding and remain responsive regardless what we throw at over the next couple of years. I’d also expect that software becomes more multithreaded aware now that intel has finally started adding more cores.

(Quite frankly I was very disappointed that when I started looking at a new machine last year intel mainstream was the same 4C/8T I have had since 2010, just with fewer dim slots and PCIe lanes - what the hell have they been doing for 7 years?)

Now if you are the only user, only play games and want to rebuild the machine every couple of years another cheap quad core might make sense. Anything else, I’d recommend getting more threads.

P4? that's a beast. My first "PC" was a 486 (After my Amiga, which was after my C-64).

Generally once you go >2 cores, the need for HT diminishes. It's typical real world benefit is something like 10-15%, which is barely noticeable.

It all comes down to how much more money 10%-15% performance gain is worth to you when deciding between and i5 and i7. It's not like i5 is every really going to limit you other than that minor 10-15% performance deficit.

 

[Paratus]

P4? that's a beast. My first "PC" was a 486 (After my Amiga, which was after my C-64).

Generally once you go >2 cores, the need for HT diminishes. It's typical real world benefit is something like 10-15%, which is barely noticeable.

It all comes down to how much more money 10%-15% performance gain is worth to you when deciding between and i5 and i7. It's not like i5 is every really going to limit you other than that minor 10-15% performance deficit.

For me I’ll prefer more cores and threads over fewer up to my budget. If I intended to keep the machine for more than a few years and do more than mainstream gaming I wouldn’t buy less than a 6 core.

4 threads has been enough over the past several years since maximum thread counts really haven’t moved past 4C/8T except at the highest end. That’s changing and I think someone who has at a minimum 6C or 4C/8T is going to be much happier than someone with 4C.


P4 was the first rig I built myself.

First that was mine was a 486 33DX

First PC that my family owned was an IBM PS2-30 286.

First access to a computer I had was through my Moms dumb terminal and 300baud acoustically coupled modem to a mainframe. She occasionally let me play Rogue or Collassal Cavern.

 

[PeterScott]

For me I’ll prefer more cores and threads over fewer up to my budget. If I intended to keep the machine for more than a few years and do more than mainstream gaming I wouldn’t buy less than a 6 core.

4 threads has been enough over the past several years since maximum thread counts really haven’t moved past 4C/8T except at the highest end. That’s changing and I think someone who has at a minimum 6C or 4C/8T is going to be much happier than someone with 4C.


P4 was the first rig I built myself.

First that was mine was a 486 33DX

First PC that my family owned was an IBM PS2-30 286.

First access to a computer I had was through my Moms dumb terminal and 300baud acoustically coupled modem to a mainframe. She occasionally let me play Rogue or Collassal Cavern.

This is really about HT.

If >4C ever becomes a must have (unlikely in the next decade), then 4C +HT aren't going to cut it either.

 

[Spjut]

This is really about HT.

If >4C ever becomes a must have (unlikely in the next decade), then 4C +HT aren't going to cut it either.

I wouldn't be so sure about that. The difference between a Haswell i3 and the Pentium G3258 is huge in modern games, some games won't even start on the Pentium, and The Division for example does "run" but you'll run into invisible walls.

And even when looking at today's games on 4C/8T vs 4C, the i5 7600k 4.8 Ghz loses to the i7 7700k at stock speed. Even the five years older i7 3770k at 4.5 Ghz is competetive to the i5 7600k and even beats it in a few games.
http://www.eurogamer.net/articles/digitalfoundry-2017-intel-kaby-lake-core-i7-7700k-review

 

[Markfw]

P4? that's a beast. My first "PC" was a 486 (After my Amiga, which was after my C-64).

Generally once you go >2 cores, the need for HT diminishes. It's typical real world benefit is something like 10-15%, which is barely noticeable.

It all comes down to how much more money 10%-15% performance gain is worth to you when deciding between and i5 and i7. It's not like i5 is every really going to limit you other than that minor 10-15% performance deficit.

I don't have a link, but I remember reading that AMD's SMT on the new Zen processors is more efficient, like 30-40% more power. I have all mine crunching, but one day, maybe I will run my own benchmarking on a TR system, and an E5-2683 system with HT/SMT on/OFF and see what it tells me.

 

[PeterScott]

I don't have a link, but I remember reading that AMD's SMT on the new Zen processors is more efficient, like 30-40% more power. I have all mine crunching, but one day, maybe I will run my own benchmarking on a TR system, and an E5-2683 system with HT/SMT on/OFF and see what it tells me.

40% is a stretch. It's more like 30%, best case, on synthetic loads.

Even then, it is most likely that just means Intel is more efficient at populating it's functional units with a single thread, which is in line with Intels better single thread IPC. What is left over for SMT/HT, are the idle units from the first thread.

 

[Iron Woode]

When I built my current rig back in 2013 I could have chosen an Haswell i7 instead of the i5 I pick and now I'm wondering if I should have given that I will not be building a new rig anytime soon.

What about now when building a new system, does it matter? And Yes I know we must also factor in cost as well. But what are you guys thoughts about this?

there is nothing wrong with a good I5 for everyday tasks and games.

As for HT:

I did a back to back comparison between a Phenom II x4 965BE and an I3 4160. Everything was the same except the MB and cpu. My 965BE and motherboard died one day. I replaced it with a Haswell I3 4160 and an Asus H81-M MB. I then ran the same tests on the Intel setup. The I3 was at least 40% faster. The improvement was felt all across the everyday activities I did, especially in multi-threaded apps. Not to mention the over 50% power efficiency. Later on I upgraded to an I5 4570. I repeated the same tests and it was over twice as fast as my 965BE was.

So HT did make a significant difference for me with the I3 and the I5 was great without it.

 

[cytg111]

When I built my current rig back in 2013 I could have chosen an Haswell i7 instead of the i5 I pick and now I'm wondering if I should have given that I will not be building a new rig anytime soon.

What about now when building a new system, does it matter? And Yes I know we must also factor in cost as well. But what are you guys thoughts about this?

As Paratus said, under specific highly threaded/parallel workload conditions it yields you 30% extra free performance. If its implementation in silicon and in terms of watts is nill on a regular basis I cant see why its not 30% winning all the way to the bank .