4 cores vs 8 cores amd ryzen

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dan
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4 cores vs 8 cores amd ryzen

Post by dan » Thu Aug 09, 2018 3:11 pm

specifically 1 brand amd
1 product ryzen

4 cores vs 8 cores ?

i'd imagine tdp of 8 cores is about 2x of 4 cores.

this is spcr so tdp and silent cooling is an issue

8 cores though sounds like the future.

the additional cost of 8 cores isn't too much, motherboard and memory is same

more cores means more energy higher utility bills

how much more difficult is it to cool silent 8 cores over 4, balanced against 8 cores offering a better experience

Abula
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Re: 4 cores vs 8 cores amd ryzen

Post by Abula » Thu Aug 09, 2018 3:53 pm

Buy what you need and what fits your budget, really you can do almost anything quiet.

I just finish my TR build with 16 cores, and i can tell you it can be manage totally inaudible at idle, depending on the load it will remain inaudible, its audible under prime95 (still quiet imo for the load) but thats a very unlikely scenario that will happen real world.

But the most important thing is to buy what you need, if you only going to use 2 cores, then buy a dual core, but if you going to use 32 cores then get it. While the prefix of more cores will require more cooling, honestly you can cool it fine, as long as you dont want a very small factor for something that needs a lot of cooling, you will be fine.

Again buy what you need atm, we are entering a CPU war, where both companies are pressuring the other, we will get octa cores at mid end setups now, i expect new cpus every year, to capture market share, AMD is coming with Zen 7nm next year, and Intel is trying to make 10nm work, at the end both architectures are very similar (watch this video), so the era of milking is over.

One last time, buy what you need right now, avoid future proofing, new stuff will come faster now.
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dan
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Re: 4 cores vs 8 cores amd ryzen

Post by dan » Fri Aug 10, 2018 5:20 am

the ravenbridge apu is attractive with 4 cores and gpu

i am wondering

will the 7nm die shrink allow for apu to go up to 8 cores since its 2x density
i understand scaling isn't 100% perfect

and then is it better to have 4 cores @ 7nm lower power

or 8 cores @ 7nm and higher power

flyingsherpa
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Re: 4 cores vs 8 cores amd ryzen

Post by flyingsherpa » Mon Aug 13, 2018 8:01 am

dan wrote:the ravenbridge apu is attractive with 4 cores and gpu

i am wondering

will the 7nm die shrink allow for apu to go up to 8 cores since its 2x density
i understand scaling isn't 100% perfect

and then is it better to have 4 cores @ 7nm lower power

or 8 cores @ 7nm and higher power
I've read decent analysis on the next gen APU (Picasso, I believe) by people who analyze the roadmap stuff and leaks and know this stuff way better than I do, and their consensus right now is that it will still be 4 core like Raven Ridge. Perhaps it will be lower power, or higher frequency or whatever, but it looks like it won't increase in cores.
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dan
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Re: 4 cores vs 8 cores amd ryzen

Post by dan » Mon Aug 13, 2018 5:07 pm

flyingsherpa wrote:
dan wrote:the ravenbridge apu is attractive with 4 cores and gpu

i am wondering

will the 7nm die shrink allow for apu to go up to 8 cores since its 2x density
i understand scaling isn't 100% perfect

and then is it better to have 4 cores @ 7nm lower power

or 8 cores @ 7nm and higher power
I've read decent analysis on the next gen APU (Picasso, I believe) by people who analyze the roadmap stuff and leaks and know this stuff way better than I do, and their consensus right now is that it will still be 4 core like Raven Ridge. Perhaps it will be lower power, or higher frequency or whatever, but it looks like it won't increase in cores.
thanks for the heads up,

well if its lower power and higher ipc i'm cool.

still torn between APU or maybe an 8 core 7nm cool running and a fanless GPU

does this mean ps5 and xbox 2 will also be 4 cores even at 7nm?

Derek Semeraro
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Re: 4 cores vs 8 cores amd ryzen

Post by Derek Semeraro » Mon Oct 08, 2018 7:13 pm

Since it's more energy efficient to have more cores rather than to have significantly higher clock speeds, it seems like the world is moving in that direction. 20 years ago many would have probably imagined a futuristic computer having a 1 core CPU at 10 GHz.

Laptops, tablets, phones and consoles are all using more cores now and desktops are taking that approach too. The 8-core Ryzen 7 is a good choice for futureproofing, though if the user only needs a 4-core CPU right now, they could buy a Ryzen 3 and then buy a 8-core CPU in a couple of years when they're cheaper.

Olle P
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Re: 4 cores vs 8 cores amd ryzen

Post by Olle P » Tue Oct 09, 2018 3:53 am

dan wrote:still torn between APU or maybe an 8 core 7nm cool running and a fanless GPU...
7nm stuff will be available some time next year, and it seems AMD will be first to it.
The base question still is what you're going to use it for!
Will you run software that actually benefit from more cores, or is it high clocks that are important?
Four cores and HT/SMT is a very good middle way...

Abula
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Re: 4 cores vs 8 cores amd ryzen

Post by Abula » Tue Oct 09, 2018 6:01 am

Olle P wrote:
dan wrote:still torn between APU or maybe an 8 core 7nm cool running and a fanless GPU...
7nm stuff will be available some time next year, and it seems AMD will be first to it.
The base question still is what you're going to use it for!
If they can make the 3700X reach close to 4.8ghz with 7nm then i go this route, else i would use them on GPUs, really need some competition there, and now that nvidia has increased the high end gpu pricing it might be very attractive for AMD if they can put something competitive.
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whispercat
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Re: 4 cores vs 8 cores amd ryzen

Post by whispercat » Wed Oct 10, 2018 10:19 am

Do AMD and Intel utilize their cores differently?

Olle P
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Re: 4 cores vs 8 cores amd ryzen

Post by Olle P » Tue Oct 16, 2018 3:19 am

Abula wrote:...If they can make the 3700X reach close to 4.8ghz with 7nm then i go this route, else i would use them on GPUs, ...
??? What is "them" here, and why would you do it?
AMD is in the late stages of migration to 7nm for both CPUs (Zen 2) and GPU (Navi), both expected to become available first half next year.
whispercat wrote:Do AMD and Intel utilize their cores differently?
Not really. The load distribution should be the same. But there are supposedly software that don't work as well with one as the other.
The main difference between AMD's Zen and Intel's Core architectures lie in the communication between the cores, and that Zen is based on four core clusters (CCX) with two CCX per die (one die for Ryzen 3,5,7 and two or four active dies for Threadripper) whereas Intel use one die per CPU no matter how many cores.

Olle P
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Re: 4 cores vs 8 cores amd ryzen

Post by Olle P » Wed Oct 17, 2018 4:29 am

Derek Semeraro wrote:Since it's more energy efficient to have more cores rather than to have significantly higher clock speeds, it seems like the world is moving in that direction. ...
I missed this one before...

I'm pretty sure power efficiency has virtually nothing to do with more cores becoming the new trend.
It's just that it's impossible (using today's technology) to have single cores run stable at significantly higher clock speeds than used today. Around 5 GHz seems to be the limit (for Intel's architecture) when the core temp is set to ~80C.

Derek Semeraro
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Re: 4 cores vs 8 cores amd ryzen

Post by Derek Semeraro » Wed Oct 17, 2018 10:33 pm

Intel themselves have stated thermals as a factor. Raising clock speeds produces more heat and requires more advanced cooling solution the further they are raised. Even if higher clock speeds could possibly be done it's just more practical to go for 6-8 cores.
https://software.intel.com/en-us/blogs/ ... ed-to-grow

Battery life is a factor for mobile devices, hence we're more likely to see a phone with eight 1.5 GHz processors than with one or two 3.0 GHz processors. Software is being developed for mobile devices every day, and these markets have been outgrowing the desktop PC. We have every reason to believe that applications in the future will make more use of multiple cores, especially when the two biggest desktop CPU manufacturers are both moving toward multi-cores.

Olle P
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Re: 4 cores vs 8 cores amd ryzen

Post by Olle P » Thu Oct 18, 2018 6:07 am

Derek Semeraro wrote:Intel themselves have stated thermals as a factor. ...
https://software.intel.com/en-us/blogs/ ... ed-to-grow
It's one of many factors, as shown.
Intel's (in)famous Prescott was running a single core at >100W while we now have roughly the same TDP for eight cores running the same frequency.

... the transistor switch speed is proportional to voltage.
Transistor speed is one of the factors limiting the maximum frequency.
I assume the switch speed is also dependent on transistor size, so going to a smaller architecture the speeds can be increased without increasing the voltage.
Power consumption with the voltage fixed is (mostly) proportional to the frequency.

Would be nice to see how a de-lidded Core i3-8350K can perform with three cores disabled while allowing the remaining core to draw ~115W (like the Prescott).
Derek Semeraro wrote:Battery life is a factor for mobile devices, hence we're more likely to see a phone with eight 1.5 GHz processors than with one or two 3.0 GHz processors.
CPUs for phones typically have 6-8 slow cores and two fast ones.
The reason being that there are several processes constantly running in the background that don't need much in terms of performance but are highly parallel. These use the slow cores.
Active apps can then use the fast cores for performance.

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Re: 4 cores vs 8 cores amd ryzen

Post by whispercat » Sat Oct 20, 2018 10:48 pm

Olle P wrote:
whispercat wrote:Do AMD and Intel utilize their cores differently?
Not really. The load distribution should be the same. But there are supposedly software that don't work as well with one as the other.
The main difference between AMD's Zen and Intel's Core architectures lie in the communication between the cores, and that Zen is based on four core clusters (CCX) with two CCX per die (one die for Ryzen 3,5,7 and two or four active dies for Threadripper) whereas Intel use one die per CPU no matter how many cores.
Thanks. I thought I read somewhere that Intel's turbo speed maxes out with only one or two cores, whereas AMD's turbo boost maxes out all cores more evenly. Maybe I misunderstood.

Olle P
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Re: 4 cores vs 8 cores amd ryzen

Post by Olle P » Tue Oct 23, 2018 5:07 am

If you're talking about "boost speeds" rather than "spreading the work load" it's also very similar between AMD and Intel.
Many high end Intel motherboards allow CPUs to run (far) above their TDP as long as the cooling is sufficient.
Look for example at HardOCP's review of the i9-9900K: At stock settings that 95W CPU runs stable at 4.7GHz pulling 158W when all cores are loaded.
On motherboards that limit the power draw to 95W it will only do 4.3GHz.
The Ryzen CPUs don't go above their TDP unless you really push them.

whispercat
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Re: 4 cores vs 8 cores amd ryzen

Post by whispercat » Wed Oct 24, 2018 12:01 am

For "spreading the work load" do Intel and AMD do anything different?

Olle P
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Re: 4 cores vs 8 cores amd ryzen

Post by Olle P » Wed Oct 24, 2018 3:19 am

I bet the code differs, but in practical terms there's no difference to the user.

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