iMac 2017 - CPU i5 3.8 vs i7 4.2

Discussion in 'iMac' started by enigma2k, Jun 6, 2017.

  1. enigma2k macrumors regular

    May 12, 2010
    What is the common consense when it comes to which processor to get for the new iMac 2017? I'm going for the model with the i5 3.8 Ghz and the Radeon Pro 580. Is it worth also getting the i7 4.2 Ghz?

    I'm sure I don't really need it but would spend the additional money if it makes the iMac more future proof since it offers hyperthreading and the i5 does not.

    Does the i7 get hotter than the i5? This is something I don't like if the fans on the i7 would run louder than on the i5.
  2. Chupa Chupa macrumors G5

    Chupa Chupa

    Jul 16, 2002
    I put my money in RAM, fast storage, and GPU. The i5 is plenty fast unless you are doing massive rapid RAW photo edits or other CPU intensive work. I feel it's better to attend to the other bottlenecks before worrying too much about getting another 30 sec of speed from a better proc.

    Also future proofing is a meaningless concept. It would be more valid if Macs were modular and upgradable. But being sealed, and the fact Apple abandons them after 5 years, means you could buy the best iMac in 2017 and it's still going to be gimped in 2022 no matter what. It will still work, yes, just likely not compatible with newer tech and features that you may want or s/w requires. So buy what you need for today and worry about tomorrow when that need arises.
  3. hydr macrumors regular

    Feb 25, 2009

    Don´t listen to all the other people here. Listen to me, and here is why:
    I owned the latest iMac 27" 5k in a i7 configuration, then sold it thinking Apple would release a new one in the end of 2016. Well, now we know they didn´t so I couldn´t live without one and ended up buying it again but this time with the i5.

    Both time I had SSD, 32GB ram.

    You know what? The difference is f´ing huge. The i7 machine was buttery smooth for me playing 4k videos and photoshopping D810 large raw files. The i5? Laggy as hell. I have been cursing ever since until yesterday. Now I´m selling my i5, and have already placed an order for a i7 4.2Ghz.

    And if you are wondering why, here is my theory regarding the i5. Driving a 5k display in all its glory is a very heavy duty process. And I think the i5 is barely able to drive it properly. Then once you start pushing it, you run into all sorts of lag.

    So to summarise: Do Not Order The i5 iMac. Put your money in the CPU. And don´t listen to anyone else who basically don´t know what they are talking about. Thank me later.

    Edit: Forgot one point. Hot? Well my i5 has been spinning the fans way more often than my i7 ever did. So no.
  4. Neo999955 macrumors member


    Jun 13, 2013
    Really? This is surprising to me. I actually ordered the i5, thinking saving some small amount of time in heavy duty tasks was a fine compromise. Has anyone else noticed serious lag due to an i5 configuration?
  5. KnoeSS macrumors member


    Sep 5, 2016
    The Hague, The Netherlands
    And what was the difference in graphics card? You're leaving that one out of the equation.

    I wouldn't worry to much though. In macos high sierra the Mac window server will run on metal 2. Buttery smooth.
  6. enigma2k thread starter macrumors regular

    May 12, 2010
    I think the reason for this must have been your graphic card and not the CPU. There is no way that an i5 will be lagging
  7. hydr macrumors regular

    Feb 25, 2009
  8. yadmonkey macrumors 65816


    Aug 13, 2002
    Western Spiral
    I'd guess that was the main difference. I think the M390 shipped with 2GB VRAM and the M395 with 4GB VRAM.
  9. btrach144 macrumors 65816


    Aug 28, 2015
    GPU doesn't do much work when editing RAW photo files.
  10. hugodrax macrumors 6502a

    Jul 15, 2007
    I would just get the i7. Not like I buy a new system every year. My 2013 mac mini with i7 quad core has been my primary machine for years and I would have gotten almost 5 years of non stop use out of it. So I went and chose the i7 and the 580 with 8gb vram. I think that will give me at least 6 or more good years of use.
  11. nambuccaheadsau macrumors 65816


    Oct 19, 2007
    Nambucca Heads Australia
    Depends a lot if you are into editing and photos..

    For mine I have found an i7 with best gfx card and adequate (24GB) of memory, whilst sure costing more, is a much easier and higher seller when it comes time to replace it. If you aim to keep thje new iMac for say four to five years, yes it will future proof it to a certain extent, as who knows what advances will be made in five years?
  12. hugodrax macrumors 6502a

    Jul 15, 2007
    Well that's the thing, you want to buy a machine that will be able to provide 5-6 years of good service. Trying to cut down to save 300-400 bucks could end up resulting in having to buy a new machine in 3 years.
  13. Jimmdean, Jun 6, 2017
    Last edited: Jun 6, 2017

    Jimmdean macrumors 6502

    Mar 21, 2007
    I've never really thought about it in terms of what you're doing, but instead how often you're doing it. Sure I handbrake a movie every now and again, but not enough to justify the extra cost. For most people it's just an added expense that yields no real benefit.

    This is only hyper-threading and just a bit of speed. Not getting it is hardly cutting corners.

    Lots of times people make it seem like more than it is. There's a reason it is only an option. Think about it like this - would you rather have burst speed on 4 cores, or normal speed on 8 cores - and which would be better for your current task? Who knows, right? That's the pickle - you really have to be able to answer those questions to know if it is a good deal for you or not.

    And the longer you keep your machine the less value it brings you in return (if you didn't really need it). 5 years from now the i5 CPUs will seriously outperform the current i7 CPUs, even in multi-threaded workloads. It's just the way the technology cycle works
  14. colodane macrumors 6502a


    Nov 11, 2012
    I think you are just fine with the i5. The configuration you are considering (High-end i5 and GPU, lots of SSD memory) should be awesome unless you KNOW you will be spending a lot of time with hyper-threading applications. Yours is the same configuration I will be ordering in the next couple of weeks. Have followed the i5 vs. i7 threads closely over the past few years and I'm very comfortable to committing to the high-end i5 CPU.
  15. jerwin, Jun 6, 2017
    Last edited: Jun 7, 2017

    jerwin macrumors 68000

    Jun 13, 2015
    The m395 had 2 GB.
    The m295x and m395x both had 4GB.

    However, the m390 had 1024 pipelines, and the m 395 had 1792 pipelines.
  16. yadmonkey macrumors 65816


    Aug 13, 2002
    Western Spiral
    My brain was stuck on the complaint about playing 4K video, but you're right about RAW photos.

    I've seen a few references to the i7s running cooler, which is reason enough for me to go that way. I hate fan noise.
  17. Jimmdean macrumors 6502

    Mar 21, 2007
    There are a lot of factors to consider, but in this case the i5's in the 27" models are 65-watt processors. The upgraded i7 processor is a 91-watt processor. If it is being taxed it will most certainly put out more heat and the system will be louder. At idle they'd all be about the same. Like I said depends on a lot of factors, but a previous point holds true - if you do not really need hyper-threading then save your money and go with the i5.
  18. saberfi, Jun 7, 2017
    Last edited: Jun 7, 2017

    saberfi macrumors member


    Oct 7, 2015
    There is an exception, the 3.8 Ghz i5 on the high-end iMac is 91W (i5-7600K)

    I would have ordered that machine in a heartbeat otherwise, but now I've spent lots of time looking at temperature graphs, power consumption measurements etc to see how hot the 7600K runs.

    I dislike fan noise more than anything else as well, which is starting to swing me for the mid-model (3,5ghz + 575 GPU), where the CPU indeed is 65W.

    So far what I've seen a gaming load test, where the 7600K takes up 10W more and runs about 7C higher in temperatures than the 7600 (which is in the mid-model).

    Still have to research it a bit more.. le sigh.
  19. fathergll macrumors 65816

    Sep 3, 2014

    Doesn't make sense to me. I have a 2014 i5 Retina iMac with a 1 TB Fusion drive and M290X and I never had a single issue with 4k video unless you're talking about editing 4K RAW in some NLE program. I've edited files from a Pentax K1(Similar 36mp sensor to the D810) and haven't had an issue unless you're talking about doing some intensive editing in Photoshop. Are you sure you didn't have the M380 vs the M390?
  20. jerwin macrumors 68000

    Jun 13, 2015

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