iMac 27" - i5 (3.8GHz) or i7 (4.2GHz)

Discussion in 'iMac' started by SirApple, Nov 29, 2017.

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i5 (3.8GHz) or i7 (4.2GHz)?

  1. i5 (3.8GHz)

    27 vote(s)
    37.0%
  2. i7 (4.2GHz)

    46 vote(s)
    63.0%
  1. SirApple macrumors newbie

    SirApple

    Joined:
    Nov 8, 2017
    #1
    Hi everyone,

    I have now decided to go for the SSD instead of the Fusion, I will go for the top model but haven't really decided where I stand with the i5 vs i7.

    How much extra juice does it give? :) Would really appreciate if anyone want to share their experience with it or any recommendations!
     
  2. Miguel Cunha macrumors 6502

    Miguel Cunha

    Joined:
    Sep 14, 2012
    Location:
    Braga, Portugal
    #2
    The best juice of the i7 is Hyper-Threading meaning you will have 2 threads per core resulting in a total equivalent to 8 cores. The i5 doesn't have this feature so it's parallel processing sticks to 4 cores. If you intend to use it with applications for heavy processing that support multicore, like filme editing, video, photography, not only you'll benefit from it, as some of those applications require the i7, due to it's hyper-threading feature.

    If on the other hand, you'll use applications with light workload, like text processing than i5 will suffice.
    I'm a film editor and I use no less than quad core i7 (due core results in lesser cores). Sometimes Xeon CPUs. I've tried with the i5 and although it runs, it's very limiting in playback, specially since 4K joined the game, so I recommend to discard anything less than i7.

    Good decision on the SSD. It´s faster and much simpler than Fusion. I also recommend only to use it as System disc, just for macOS and applications. Buy an external storage, preferably a RAID, with no less than 7200 RPM and configure it to RAID 0, for maximum speed, or if it has at least 4 drives, to RAID 5, for a balance between speed and redundancy - If one of the drives fails, you're still safe and can replace it, without any loss of data.

    Hope this helps. ;)
     
  3. SirApple thread starter macrumors newbie

    SirApple

    Joined:
    Nov 8, 2017
    #3


    Hi Miguel, thank you for your response :)

    I think I will end up with the i7 to make the computer a bit more future proof.

    In terms of the setup with an external storage; that could a smart setup to make sure that everything runs smoothly. I also plan to install Windows on bootcamp.

    Any recommendation for external storage? I guess I would like something in the line of 1-2TB.

    Thanks

    //SirApple
     
  4. Glideslope macrumors 603

    Glideslope

    Joined:
    Dec 7, 2007
    Location:
    A quiet place in NY.
    #4
    I agree with all of Miguel’s post. I have the 3.8 i5 in my 27” with the SSD. I really have no need for Hyper Threading. So I went with the 3.8 and used the difference to go with the 1TB SSD. I have no regrets. IMO the i5 will be the sweet spot in the new 8600K series chips in the 2018 iMac as well. As Miguel stated his Workflow is a must for the i7. Lots of users in here with 3.8 i5 that don’t do Pro Video are very happy with the 7600K.

    I have always used WD external drives for my onsite backups. Never had a serious issue. A good rule of thumb is twice the capacity of the main drive. I also run a Samsung T3 512 SSD USB-C as an external boot disk for some non essential applications I don’t want on my main drive. I also feel 32g is the max ram anyone would need running 10.12. 10.13 is a PITA. Hopefully your machine has 10.12.

    Either way you’ll love your new iMac. :apple:
     
  5. jzuena macrumors 6502a

    jzuena

    Joined:
    Feb 21, 2007
    Location:
    Lexington, MA, USA
    #5
    If you plan on using Apple's BootCamp installer, the Windows system disk will have to be on your internal drive, so you may want to get at least a 512GB SSD (that's the smallest SSD on the top tier, but 256GB is available on the entry and mid tier). You can give Windows as low as 50GB and set it up with external storage as well for the D: drive. There are ways to install Windows on the external drive instead, but they aren't supported by Apple. If you decide to also run your BootCamp partition as a virtual machine, save yourself some grief and just go with the Apple-supported internal drive install. I hosed my BootCamp partition on an external drive when I tried opening it as a VM, so I relented and reinstalled on the internal drive.

    For external storage, look for at least USB-3 (preferably USB 3.1), and if you can find a good price, get Thunderbolt 3/USB C. I have 3 USB-3 drives that came over from my mini... I gave my mom my USB-2 drive with the mini. I have a 2TB Time Machine drive, a 2TB miniStack, and a 2-drive IcyDock with two 1TB drives in it. The IcyDock is the only one that isn't passively cooled, so you can hear the fan over the Mac's fan. It's not super loud, but you can hear it. It can be set up in a RAID configuration, as two separate disks, or as a single JBOD logical drive. Its still a good drive (its my only USB 3.1 drive), just plan on putting it behind your iMac to block some of the sound.
     
  6. satinsilverem2 macrumors 6502a

    satinsilverem2

    Joined:
    Nov 12, 2013
    Location:
    Richmond, VA
    #6
    I would get the i7 just for future proofing. I always max out the graphics and processor when I buy a new machine. You can always upgrade the storage and ram at a later date if you want to especially in the desktop machines.
     
  7. gian8989 macrumors regular

    Joined:
    Oct 23, 2015
    #7
    Everyone here are saying i7 but you still didn't say what you are going to use the iMac for.
     
  8. EugW, Dec 3, 2017
    Last edited: Dec 4, 2017

    EugW macrumors 601

    EugW

    Joined:
    Jun 18, 2017
    #8
    Exactly. Also, it depends on how sensitive you are to noise.

    I bought the i7 with 1 TB SSD but was annoyed that it would rev up the fan to max very quickly under full load. So I returned it and got the i5-7600 3.5 GHz, again with 1 TB SSD. Much happier, since in truth I don't absolutely need the extra speed.

    BTW, to give you an idea, with video encoding in Handbrake (which I only do occasionally), on the i7 it took 10 minutes, but with the fan on max for 9.5 minutes. The same video encode on the i5 3.5 GHz took 12.5 minutes (25% longer), but with the fan audible (not at max) just 2-3 minutes at the end.
     
  9. SirApple thread starter macrumors newbie

    SirApple

    Joined:
    Nov 8, 2017
    #9

    I am going to use it for some quite heavy MS Excel, gaming (mostly through bootcamp Windows) and some hobby level photo/video editing. I have read a bit about the noise level in some of the other threads, how bad is it? What would you recommend?
     
  10. J.Gallardo macrumors regular

    J.Gallardo

    Joined:
    Apr 4, 2017
    Location:
    Spain
    #10
    I’ve just ordered an i5 iMac. I don’t need hyperthreading, but I could have paid the extra thinking about “future-proofing”.
    Why didn’t I?:
    Noise is the symptom. It’s not the real problem, I think. Just pump up the music!
    Noise is because fan spinning. Fan throttle is because sudden highs in temperature. Intel i7 reaches 100°C easily and iMac seems like a vacuum-cleaner (no good on my messy desk, full of papers and inherent dust).
    My last iMac was i7 (late 2009). It broke because of failing micro-solderings in gpu (not in mainboard... but heat reaches every part of the machine, and worse, it keeps getting hot and cooling down). Intel i7 is a unique upgrade on systems designed with i5 thermal behavior in mind (just one fan!).
    If you make big money with rendering or movie processing, you should get the i7 (time is gold). Many pro’s just change system in a couple years, selling a functional iMac and getting a next gen one.
    I’m a particular, a high-school teacher: “future-proof” is to me making my mac to last for longer time. So I stayed with Apple’s “recommended” i5.
     
  11. Mac32 Suspended

    Joined:
    Nov 20, 2010
    #11
    For gaming in 2560x1440, will the i7 CPU give noticeably better framerates or framerate stability (vs i5)?
     
  12. J.Gallardo macrumors regular

    J.Gallardo

    Joined:
    Apr 4, 2017
    Location:
    Spain
    #12
    Actual games don’t use hyperthreading (it can change in near future). I7 will be a little more faster because of physical core’s peak speed. But I bet gpu (& gpu RAM) is more critical for games, and will benefit overall system graphical performance.
     
  13. SirApple thread starter macrumors newbie

    SirApple

    Joined:
    Nov 8, 2017
    #13

    So you are basically saying that unless I need the iMac for heavy video editing then it is a waste going for the i7 due to the fan noise?
     
  14. EugW macrumors 601

    EugW

    Joined:
    Jun 18, 2017
    #14
  15. J.Gallardo macrumors regular

    J.Gallardo

    Joined:
    Apr 4, 2017
    Location:
    Spain
    #15
    In fact, this comparative is not fair. Is i5 WITH 575gpu (4gbRAM) vs. i7 WITH 580gpu (8gbRAM).
    I’ve been searching the web and couldn’t find an i5 vs. i7 with same gpu comparative. But seeing those numbers, and these http://barefeats.com/xplane11.html , I guess gpu makes the difference.
    --- Post Merged, Dec 4, 2017 ---
    I don’t mind noise.
    I fear going near heat limits, making fan work heavier, heating/cooling variations against keeping constant medium temp., more and intermittent suction highs from air intake holes...
    I wonder why Apple doesn’t offer a top iMac tier with i7 as base model. I wonder why next iMac Pro has a totally redesigned cooling system.
    My last iMac died because of heat; I wonder if it could have lasted a couple years more with a cooler cpu. Not being sure, but not being in rendering or heavy tasks, I prefer to please Mother Nature and not mount the biggest and hottest engine in my “car” (considering every other component is the same for standard engine).
     
  16. MCAsan macrumors 601

    MCAsan

    Joined:
    Jul 9, 2012
    Location:
    Atlanta
    #16
    The linked site gives a good comparison between the processing power of the iMacs and Mac Pros CPUs on single core and multi core tasking.

    Note:
    • Newer iMacs can be faster than Mac Pros at single thread apps.
    • i5 3.8 is close to 4.2 i7 at single thread apps....and so could be all someone needs
    • On multi thread apps is where Mac Pros shine with 8 and 12 cores
    • On multi thread apps you a noticeable gap between i5 3.8 and i7 CPUs.....could be important if running multithread apps (you need to know what type of apps you will be running)
    • iMac Radeon 575 and 580 both have more processing power than Mac Pro D700
    https://www.geekbench.com/blog/2017/06/imac-27-inch-performance-june-2017/


    To try to get the max bang for the buck and longest life span...I went with:
    • i7 4.2
    • Radeon 580
    • 512 SSD (more than enough room for MacOS, boot, apps, caches..etc. (with over 200 still available)
    • 8GB memory because I got 16GB Crucial and now have 24GB for less cost than 16GB from Apple
    • Got it from B&H Black Friday special for $200 off plus no tax or shipping
    • Hooked up my previous external TB 2 RAID drive sets using the TB to USB-C adapter from Apple (will one day move to native USB-C/TB3 native drive enclosures)
     
  17. EugW macrumors 601

    EugW

    Joined:
    Jun 18, 2017
    #17
    Good point about the GPU, J.Gallardo. Actually I’m surprised at how well the 575 does in comparison to the 580.
     
  18. gian8989 macrumors regular

    Joined:
    Oct 23, 2015
    #18
    I don't think that i5 is a necessity for you (but I am not realy sure how taxing is excel for CPU) but if noise is not a problem and the difference in price doesn't bother you i7 is definitely faster.
    I have an i7 and the cpu temp reach 90° only with video editing and gaming (I only tried one game to test cpu and fan so I am not sure how it is for long sessions of gaming). I probably notice the noise more because i usually have the volume at the lowest possible level. If you are someone that has the volume up it will cover the fan noise. I don't think that the fan db is that high, what bothers me a bit is the kind of sound more similar to a vacuum cleaner.
     
  19. J.Gallardo, Dec 4, 2017
    Last edited: Dec 4, 2017

    J.Gallardo macrumors regular

    J.Gallardo

    Joined:
    Apr 4, 2017
    Location:
    Spain
    #19
    That made me think that perhaps i5 or i7 is not a difference in games.
    You can see as disabling Turbo in i7 makes no difference, and it’s not really noticeable in i5.
    Intel i5 with Turbo reaches 4.2Ghz. Intel i7 with turbo-off runs at 4.2Ghz. If no hyperthreading is involved, both i5 & i7 with 580 gpu performance could be indistinguishable. Maybe the gpu is the “bottle-neck” for games.
    ...But it’s just my opinion...o_O... As I’ve said, no such a comparative in www.
     
  20. Fishrrman macrumors G5

    Fishrrman

    Joined:
    Feb 20, 2009
    #20
    OP:

    The "best balance" between power/quietness/price is the 7600 CPU on the "midrange" model (3.5ghz). Decent GPU as well.

    Of course, get either a 256gb or 512gb SSD instead of the fusion drive.

    'Nuff said!
     
  21. J.Gallardo macrumors regular

    J.Gallardo

    Joined:
    Apr 4, 2017
    Location:
    Spain
    #21
    Agree.
    The most important and expensive part of an iMac is the screen (IMHO).
    OP: Get the 27” because you’ll be always enjoying it...7600 cpu is the best balanced for money option. And SSD seems the way to go (I’ve ordered 1tb ssd).
    But if you want to keep all “your things” in an only logical volume & don’t want to mess with external disks, going Fusion is not crazy to save some more money. The 2tb Fusion gives you a 128gb SSD...
    (...just pointing SCREEN is the value...)
     
  22. EugW macrumors 601

    EugW

    Joined:
    Jun 18, 2017
    #22
    I have the 7600, but the 7600k is a reasonable option too, if you want the faster GPU.
     
  23. Miguel Cunha macrumors 6502

    Miguel Cunha

    Joined:
    Sep 14, 2012
    Location:
    Braga, Portugal
    #23
    For creative work, specially video editing, the i7 quad core is the minimum for a performance, without lagging.
    Although some software houses may still consider the i5 or a dual core i7 in their minimum system requirements, in the real world the difference can be dramatic. My recommendation is not aimed only at longer lasting tool, but a smooth workstation. Even if video editing is just a hobby, after realizing what can be done with the processing power, everyone tends to get enthusiastic, adding layers and effects. Sooner than expected people evolve their hobby in to something more demanding - which is wonderful.
     
  24. EugW macrumors 601

    EugW

    Joined:
    Jun 18, 2017
    #24
    Some of the 2018 i5 machines will be 6-core. This will change the equation.
     
  25. topgunn macrumors 65816

    topgunn

    Joined:
    Nov 5, 2004
    Location:
    Houston
    #25
    I have purchased three current gen 27" iMacs; 3.5 w/ 575, 3.8 w/ 580, and 4.2 w/ 580. Noise is a big deal to me. All of these iMacs are quiet until they start to hit 100 degrees C at which point the fans become audible. The 3.5GHz iMac rarely (almost never) hits 100C and thus stays silent 99.9% of the time. The 3.8GHz iMac with the 580 will get just up to 100C and hand out around 95-98C. The 580 does get a bit warmer and you'll hear the fans kick off from time to time because of the GPU. The 4.2GHz iMac would hit 100C doing odd tasks like updating a bunch of Dropbox files or on random webpages.

    So, I stuck with the 3.8GHz machine with the 580. I don't miss hyper-threading too much, I get the 580, and I don't have to endure the high-pitched whine of the iMac with the i7.
     

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