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Forum: Hardware Chat Room
Thread: Intel Coffee Lake crunching results and experience? |
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Thread Status: Active Total posts in this thread: 31
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wolfman1360
Senior Cruncher Canada Joined: Jan 17, 2016 Post Count: 176 Status: Offline Project Badges: 
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Hi,
----------------------------------------So, I figure it's time for an upgrade. Replacing my aging fx8350, which is still holding up handsomely after 5 years. Looking at the Dell xps 8930 SE. Does anyone have experience crunching with these brand new processors (core i5-8400, i7-8700 and i7-8700K? Does the k series really make a huge difference in crunching as I'm only gaining maybe 200 MHZ in turbo boost? I'm also guessing the regular, non overclockable 8700 uses less power overall seeing as TDP is 65 watts. Any help appreciated! thanks.
Crunching for the betterment of human kind and the canines who will always be our best friends.
AWOU! |
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
No experience with Coffee Lake. But some thoughts on the K-Series:
My experience is, as you already guessed, that these don't add too much in computing power but increase electricity consumption dramatically. In general, with the same CPU design, it is always more efficient to have a lower clock rate, as with higher clock also voltage must be increased, which increases electricity consumption disproportionally. I even once tried with a i7-3770, if it does pay off to activate turbo boost (which let's all cores run at 3,7 GHz instead of 3,4 GHz). The result depends on electricity cost, hardware cost, how long you plan to use the hardware - with my parameters it didn't pay off, so I let it run without Turbo Boost. For the same reason, Xeons are more efficient, with more cores but lower clock rates. |
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KerSamson
Master Cruncher Switzerland Joined: Jan 29, 2007 Post Count: 1684 Status: Offline Project Badges: 
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In my understanding, the Turbo Boost does only apply if the CPU load is low. As soon the CPU load is 100% - usually the case if boinc is running on a desktop or on a server, the Turbo Boost does not work.
----------------------------------------Maybe the strategy is different for the newest CPUs, but in the past the Turbo Boost only worked if the CPU was not already fully load. Cheers, Yves |
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SekeRob
Master Cruncher Joined: Jan 7, 2013 Post Count: 2741 Status: Offline |
My I7-4770K, standard at 3.4Ghz, runs 3.7 if I setting the power setting to max, 100% CONSTANTLY. Only when set at 99% will it flat out run 3.4, but maybe my Intel comes from a different factory.
----------------------------------------Turbo Boost is scaled, as when only running BOINC 4 threads, it runs at 3.9 and when 2 threads it runs 4.1 max. [Edit 1 times, last edit by SekeRob* at Oct 25, 2017 9:08:49 AM] |
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wolfman1360
Senior Cruncher Canada Joined: Jan 17, 2016 Post Count: 176 Status: Offline Project Badges:
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So I should go with the i7-8700?
----------------------------------------I just looked. Max turbo boost is 100 MHZ less. How do they get away with that and use 30 w less power? This is in a more compact case - will this effect performance of the turbo boost? Regardless of what I get this will definitely be more efficient (and powerful) than my fx8350. Intel sure had to scramble to make 6 core CPU's with Ryzen, and I wonder how they're comparing. I'm also reading these processors are running hotter and that the fans on this xps have to run quite a lot harder vs last year with the 7xxx series. I wish Dell would come out with a ryzen XPS. Alas.
Crunching for the betterment of human kind and the canines who will always be our best friends.
AWOU! |
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TitusFCR
Advanced Cruncher United States Joined: Feb 8, 2007 Post Count: 53 Status: Offline Project Badges:
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The Intel K series processors allow overclocking, therefore they need a higher TDP to allow for that. If you are not overclocking, then the i7 8700 is the better choice (vs i7 8700K).
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
In my understanding, the Turbo Boost does only apply if the CPU load is low. As soon the CPU load is 100% - usually the case if boinc is running on a desktop or on a server, the Turbo Boost does not work. In a sense this is true, if you mean the maximum Turbo Boost Frequency, wich does only apply if one core is used. However, there are multiple maximum Turbo Boost frequencies depending on the number of cores used. The more cores are used, the lower the Turbo Boost frequency. But even if all cores are 100% used, the possible Turbo Boost frequency is higher than the base frequency of the processor. If the max Turbo Boost is really reached, depends on actual current, temperature etc. of the CPU. The CPU adapts its maximum frequency dynamically depending on these parameters. From own experience: my i7-3770 (standard 3,4 GHz) crunches 24/7 with 3,7 GHz which is the maximum Turbo Boost with load on all 4 cores. If this works on all or most CPUs generally I cannot say. Anyone more experience? So I should go with the i7-8700? I just looked. Max turbo boost is 100 MHZ less. How do they get away with that and use 30 w less power? Keep in mind that the TDP wattage is Thermal Design Power. This can be a rough guide if a processor uses more or less electricity, but not more. All in all I doubt that the 8th generation core processors are the best choice for a cruncher in all cases. Sure, they are faster and more efficient, but 2 older PCs are also faster, and while they are less efficient they cost less in the beginning. So I would say if you electricity cost is very high, the i7-8xxx could make sense, if not, a used PC, maybe even as old as an i7-4xxx could make sense. But when choosing between i7-8700 and i7-8700K, I would choose the non-K, for a cruncher, if you have to pay for your electricity. |
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wolfman1360
Senior Cruncher Canada Joined: Jan 17, 2016 Post Count: 176 Status: Offline Project Badges:
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In my understanding, the Turbo Boost does only apply if the CPU load is low. As soon the CPU load is 100% - usually the case if boinc is running on a desktop or on a server, the Turbo Boost does not work. In a sense this is true, if you mean the maximum Turbo Boost Frequency, wich does only apply if one core is used. However, there are multiple maximum Turbo Boost frequencies depending on the number of cores used. The more cores are used, the lower the Turbo Boost frequency. But even if all cores are 100% used, the possible Turbo Boost frequency is higher than the base frequency of the processor. If the max Turbo Boost is really reached, depends on actual current, temperature etc. of the CPU. The CPU adapts its maximum frequency dynamically depending on these parameters. From own experience: my i7-3770 (standard 3,4 GHz) crunches 24/7 with 3,7 GHz which is the maximum Turbo Boost with load on all 4 cores. If this works on all or most CPUs generally I cannot say. Anyone more experience? So I should go with the i7-8700? I just looked. Max turbo boost is 100 MHZ less. How do they get away with that and use 30 w less power? Keep in mind that the TDP wattage is Thermal Design Power. This can be a rough guide if a processor uses more or less electricity, but not more. All in all I doubt that the 8th generation core processors are the best choice for a cruncher in all cases. Sure, they are faster and more efficient, but 2 older PCs are also faster, and while they are less efficient they cost less in the beginning. So I would say if you electricity cost is very high, the i7-8xxx could make sense, if not, a used PC, maybe even as old as an i7-4xxx could make sense. But when choosing between i7-8700 and i7-8700K, I would choose the non-K, for a cruncher, if you have to pay for your electricity. How is an older PC faster? I get that it costs less - but faster in what way? I'm likely going with the 8700. I have no interest in overclocking since, me being blind, I have no way to actually view the bios and I want longevity over speed. I'm going to assume, though, that core for core, since the i5 is not hyper threaded it would go faster per core than the i7? Or am I wrong in thinking that? My i5 2400 crunches MCM's faster than anything else I own, for instance. I'd be curious if the max turbo boost frequencies are being met with these new 6 core processors. Now intel doesn't specifically state the max turbo boost with all cores active so I'm going to assume that this means some processors are going to be worse than others as far as power and temperature from the factory? Does having the k series also mean that, despite 95 w TDP, it may only use 70 W or so if not less and the 8700 may only use 45 or 50 etc? Does anyone have a 7xxx series? Pretty much anything will beat this fx right now so that's an option, too.
Crunching for the betterment of human kind and the canines who will always be our best friends.
AWOU! |
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TitusFCR
Advanced Cruncher United States Joined: Feb 8, 2007 Post Count: 53 Status: Offline Project Badges:
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Here is a link to an article on the Coffee Lake processors. It contains a chart showing the max turbo boost frequencies for the Coffee Lake lineup. The max turbo boost an individual core can reach is dependent on how many of the cores on a processor are called into service. For example, the i7 8700 can reach a max turbo frequency of 4.6GHz for a single core, but only 4.3GHz if all 6 cores are being used.
----------------------------------------https://www.anandtech.com/show/11859/the-anan...-and-8400-initial-numbers [Edit 2 times, last edit by TitusFCR at Oct 25, 2017 9:49:32 PM] |
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
How is an older PC faster? I get that it costs less - but faster in what way? My thinking was the following: 1.) yes, a newer PC is faster than an older one, but it also costs more 2.) you could as well buy multiple older PCs, they are also faster than a single old PC option 1.) is more energy efficient than option 2.). But which one is actually the most cost effective, depends on specific prices, energy efficiency and electricity cost. Buying the newest CPU is not always the best option for maximizing WCG points / $ spent. Does having the k series also mean that, despite 95 w TDP, it may only use 70 W or so if not less and the 8700 may only use 45 or 50 etc? Not sure about the actual power consumtion. But I would expect the i7-8700 to consume exactly the same as the i7-8700K, as Turbo Boost with load on all 6 cores is 4.3 GHz on both. The difference is, the i7-8700K can be overclocked, and if you do so, it will consume much more than the 8700 ever will. I'm going to assume, though, that core for core, since the i5 is not hyper threaded it would go faster per core than the i7? Or am I wrong in thinking that? Correct. Hyperthreading makes one core faster by running two threads simultaniously on it and therefore better utilizing its capacity. You double the number of threads, but every thread is slower. However, every thread is faster than half the speed without hyperthreading and therefore you gain some speed overall. |
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