i7-7700K vs i5 7600K comparison - Which one will you get?

Discussion in 'iMac' started by Torgo81, Jun 10, 2017.

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Which CPU will you get?

  1. I will get the i5

    33 vote(s)
    47.8%
  2. I will get the i7

    36 vote(s)
    52.2%
  1. Torgo81 macrumors newbie

    Torgo81

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    Oct 20, 2012
    Location:
    Amsterdam
    #1
  2. Moriarty macrumors 6502

    Joined:
    Feb 3, 2008
    #2
    I got the i5. Most reports say that it uses much less power under load (~65W vs ~90W). Those extra 300 MHz can make the iMac run hotter and louder.

    Synthetic benchmarks are ********. The multicore is made specifically to show off the advantages of hyperthreading. For many workloads in the real world, hyperthreading has little benefit and the i7 is only ~7% faster than the i5. Well-written code that can always keep the CPU busy with only four threads can actually be slower with hyperthreading.

    For me, 7% extra performance is not worth the extra heat and noise.
     
  3. koyoot macrumors 601

    koyoot

    Joined:
    Jun 5, 2012
    #3
    And Core i5 in 90% of the time, under load is loaded up to 95%, because of lack of throughput, where Core i7 is still hovering around 60-70% load on cores, snd is effectively cooler, and still has enough horsepower to do more stuff than Core i5 can. It is 2017, Ryzen 8 core have opened peoples eyes about this factor.

    Simplest answer. Take the highest amount of threads you can afford. It is way more worth it than you think. Software is catching up very fast. Hardware cannot and very soon you might regret getting only Core i5, instead of Core i7.
     
  4. Glideslope Suspended

    Glideslope

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    #4
    i7. It's by far the choice for any large photo/video editing. The i5 is fine for web browsing and Apple Photos. ;)
     
  5. Moriarty macrumors 6502

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    Feb 3, 2008
    #5
    By that analogy, you imply that the i7 is 35% faster than the i5 (95/70 = 35). That's only occasionally true, as any real-world benchmark shows. Many tasks are only ~7% faster with the i7 (that's the clock speed difference). Any workload that pegs the CPU to its max frequency (e.g. coding, compiling) will consume more watts on the i7, because the jump from 4.2 GHz to 4.5 GHz is really inefficient. Effective hyperthreading also produces more heat.

    If you have a workload that does not peg the CPU to 100% (e.g. real-time audio stuff), I agree that the i7 may be a little bit cooler. Mostly because it's likely to be a better quality chip, and can run at a slightly lower voltage at each frequency. However, if the CPU isn't producing enough heat to spin up the fans, I don't care if my i5 draws 35W and the i7 draws 32W.

    My workload is mostly the former case – my CPU is either at 100% or 0%. I'd rather wait 10% longer and have a CPU that produces 25% less heat and doesn't rev the fans up.
     
  6. koyoot macrumors 601

    koyoot

    Joined:
    Jun 5, 2012
    #6
    If you have an application that loads the CPUs in the same manner it will behave differently on both CPUs.

    What this means? Core i5 will be 90% of the time loaded around 95% on all cores, and heat up to the max. Core i7 will hover around 60-70%, and still have room for more work to do, and also will be cooler to run, because it is not fully loaded.

    Real world benchmarks have opened peoples eyes about this. The problem which you do not understand is that Software matures and over time, your Core i5 will get much slower than Core i7, because of lack of Hyper Threading. Get as many cores and threads as possible for particular price point. I "like" when people say about future proofing their expensive computers, and then get away with Quad Core/Quad Thread CPU, because today its not important to have more.

    Paradigm has shifted. Ryzen has brought 8 cores to mainstream and there will be much more software optimized for high core count scenarios. Nobody optimized for those scenarios before, because Intel was enjoying their dominance, and offered only 4 cores as mainstream. This is the reason for paradigm shift.

    Lastly. Your iMac will rev the fans regardless of the thermal output you have. Why? Because fan spinning is caused by CPU temperatures, and you will always get it heat up to 90 degrees in seconds after loading it up.

    In essence. You will not see any benefit of going with lower power TDP CPU, fans ALWAYS will ramp up under load, but your iMac will get old much faster than Core i7 based will.
     
  7. klatox macrumors member

    Joined:
    Dec 24, 2015
    #7
    Wow, I'm surprised they put a 7700k in an iMac...that's usually what gamers use and they normally overclock it!

    Seems that if you're going to be doing anything that requires more multithreaded performance, then the i7 is the way to go. That processor is currently $329 by itself (not including cooler), so $200 to bump up to it seems like a good deal.
     
  8. trsblader macrumors 6502

    Joined:
    May 20, 2011
    #8
    I am debating on the i7 but don't think I'll get it. I do some encoding and short videos (just throwing clips together from trips sort of thing). The few seconds I'll save once or twice a week doesn't seem worth it to me when I'm not earning money from this work and am just doing it for fun.
     
  9. Torgo81 thread starter macrumors newbie

    Torgo81

    Joined:
    Oct 20, 2012
    Location:
    Amsterdam
    #9
    So far the reasons for the i7 are photo/video editing. What about gaming? Will there be a (significant) benefit of having an i7 instead of i5 either in combination with the Radeon 580 or in the future with a faster eGPU?
     
  10. Quash macrumors regular

    Joined:
    Sep 27, 2007
    #10
    For gaming it makes no difference (for almost all games). You're probably better off with the i5. Because both the cpu and the gpu use the same cooling system. The i5 uses quite a bit less power thus leaving more thermal headroom for the GPU. (around 20w according to tomshardware)
     
  11. Moriarty macrumors 6502

    Joined:
    Feb 3, 2008
    #11

    I found an old review (in French) of the 2014 iMacs, that did a comparison between the i5 and i7 versions. I'm pretty sure that this situation will hold more or less true with the 2017 versions.

    TL;DR: at full CPU load, the i5 CPU consumes about 60 W and the fans stay at the idle 1200 rpm. However, the i7 consumes 85 W at full load and the fans spin at 2400 rpm.

    I don't know if the i7 / 580 system will thermally throttle, but picking the i5 will certainly result in a cooler-running system that's less likely to blast the fans at maximum rpm. If that's your priority, get the i5. If absolute performance is your priority, get the i7.
     
  12. jerwin macrumors 65816

    Joined:
    Jun 13, 2015
    #12
    I have a 2014 imac with an i5. In my experience, the fan usually idles at 1200 rpm, except when I'm playing games, and the GPU is very active. I suppose I don't peg the CPU hard enough to trigger the fan. It can be done, however, using Prime95. The fan cycled up to 2700 rpm quite readily.

    Still, I doubt that a fourth generation Core i5 is that comparable to seventh generation i5-- at least in terms of power handling.
     
  13. freebo27 macrumors newbie

    Joined:
    Jun 8, 2009
    #13
    I went the i7 because it didn't cost that much more and the extra cores will help when I run VM's. In fact due to my work I may leave a Win10 VM running permanently.

    I'm hoping it won't be too noisy though.
     
  14. Firebrand macrumors regular

    Joined:
    Sep 13, 2016
    #14
    i5 or i7, both are very good cpu’s.
    I say: buy i5 now, and save your money for a future new iMac (with new i5). Forget about the i7.
    (Except maybe if your into gaming, video or that kinda stuff.)

    Eventually you’ll want a new iMac in the near future anyway.
     
  15. Quash macrumors regular

    Joined:
    Sep 27, 2007
    #15
    This is solid advice in my experience, iMacs have really really good resale value. But most of the extra money you put into maxing out an iMac you will not get back. It's better to upgrade every 3 years instead of future proofing into a max iMac and use that for 5 years. Also i've had quite a lot of trouble with maxed out GPU's in my past iMacs. But that 580 looks tempting though, i have to admit :)
     
  16. Firebrand macrumors regular

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    Sep 13, 2016
    #16
    Another great tip is not to buy impulsive. Better to wait until the :apple:fog clears ;-)
     
  17. cal6n macrumors 68000

    cal6n

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    Gloucester, UK
  18. Torgo81 thread starter macrumors newbie

    Torgo81

    Joined:
    Oct 20, 2012
    Location:
    Amsterdam
    #18


    This was posted in another thread and is pretty awesome as it shows the difference between the i7 and the i5 in many different games. For CIV VI there is not a big difference in FPS but I guess whn you said CIV VI feasts on threads that mostly happens at the end of turn calculations, which can take long? (On my 2012 i5 21.5 inch iMac CIV V took a long time, never tried CIV VI)
     
  19. cal6n macrumors 68000

    cal6n

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    Jul 25, 2004
    Location:
    Gloucester, UK
    #19
    Yeah. Threading drives the turn times in Civ 5 and 6. I'm hoping the 580's 8GB will allow all the eye candy too.
     
  20. propower macrumors 6502a

    Joined:
    Jul 23, 2010
    #20
    I find the opposite true in the 2017 iMac. I have the Base i5 and i7 BTO in house now. 100% load on the i5 3.4 (33.4W) = 66degC. 51% load on the i7 (69W) = 95degC and Full speed fans. The cooling system in all iMac 27" machines is the same. The i7 runs WAY hotter than the Base i5.

    I have also tested ProAudio apps with i7 Hyperthreading on and off (2017 iMac). The CPU load is 2X with HT off (as expected) and the temps are almost identical. HT lets One core do two things (if possible) - but its still one core. For the same load with HT On or OFF the temps are the same.

    HT CPUs can absolutely do more than non HT. Real world for me has been in the 20 to 30% range. This may or may not make a difference to a persons application.
     
  21. EugW, Jun 25, 2017
    Last edited: Jun 25, 2017

    EugW macrumors 68020

    EugW

    Joined:
    Jun 18, 2017
    #21
    I think you're both right in a way. The caveat here is you're comparing two different classes of chips. The 7500 is a 65 W chip at "full" power. The 7700K is a 91 W chip.

    IMO the ideal chip might have been the Core i7 7700 (non-K). It is a 65 Watt chip, but which has a base clock of 3.6 GHz and a Turbo of 4.2 GHz, and HyperThreading. Best of both worlds IMO. Unfortunately, Apple decided to put it in none of the Macs.

    Anyhoo, I just imported about 5 GB of photos into Photos, and the fan didn't speed up even once IIRC. It was probably more I/O limited though, since my iPhone cable is USB 2. I'll have to try to get an USB 3 iPhone cable when one comes out, as my iPhone 7 Plus is capable of transferring at USB 3 speeds.
     
  22. rico7578 macrumors newbie

    Joined:
    Jun 20, 2017
    #22
    For me it is far too optmistic related to softwares effectively using mutliple core (more than 4) !
    Multicore appeared years ago now, and today only few softwares (video editing maybe or heavy parallel calculation software) really take advantage of them.
    But the vast majority of softwares available today benefit firstly from high Ghz speed and only 2 or 4 cores max are used.
    Indeed, it is not easy to use multiple core, and it depends of what is requested by the software. In random calculations, you just can't put in paralell the compute, you can only serialize it.
     
  23. macsplusmacs macrumors 6502

    Joined:
    Nov 23, 2014
    #23
    Anyone know if Xcode 8 and 9 feasts on threads? Its the app i would be using the most.

    (on a SSD)
     
  24. iemcj macrumors 6502

    iemcj

    Joined:
    Oct 31, 2015
    #24
    Very few games are going to bottleneck with the cpu. It'll have it's biggest uses in rendering, batch work (think lightroom exports, video conversion, ect), and with mmo type games with a lot of mulitplayer since that can get cpu dependent. Star Wars the Old Republic is a great example of this, not much needed gpu wise but it needs a fairly strong cpu to keep up.
     
  25. Falcon80 macrumors 6502

    Joined:
    Oct 27, 2012
    #25
    Would be interested to know as well. :)
     

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