Previous Gen i7 vs. current i5 for longevity

Discussion in 'iMac' started by sasha.danielle, Mar 25, 2016.

  1. sasha.danielle, Mar 25, 2016
    Last edited: Mar 25, 2016

    sasha.danielle macrumors regular

    Joined:
    Mar 15, 2015
    #1
    Hi folks,

    I'm thinking about dropping some coin this fall on a 27 in iMac retina (I wanted to last year, but other expenses came up). I've seen some youtube videos, and noticed on GeekBench too, that previous generation i7 machines solidly beat out current generation i5 models.

    This guy compares a Haswell i7 to a Skylake i5 and the Haswell beats it out.


    GeekBench also shows that not only does the 2013 i7 beat out current i5 on single core tests, but even the 2012 i7 handles the current model on multi-core tests.
    https://browser.primatelabs.com/mac-benchmarks

    Now, I'm not a power user (I think that most people who think they're power users really aren't, but that's another topic altogether). I'm a writer, and an academic, so the primary function of the machine is writing, and watching movies. As well, I'm a musician and hope to start working more in Logic, but I'm also about to start my Phd, so I'll probably be too busy in the next 5 years (during the life cycle of this machine) to do as much recording as I'd like to.

    1) That said, I want to spend my money appropriately, so I'm considering buying a refurb previous gen retina iMac with an i7 or a new a new i5 on an education discount. All things being equal (RAM, SSD, etc.), which is the better buy for longevity?

    2) Also, heat has been a problem with iMacs, and seems to be the biggest repair factor in these machines, so maybe the i5 is less taxing on the machine in the long term?

    3) I'm also starting to think that the best thing to do with Macs is to keep them for the duration of Apple Care and then sell them at the 3 year mark when their resale value is still high. In this case, it would seem prudent for me to go with an i5 BTO w/ SSD.

    4) My last question is how much does the i5 3.3 GHz (as opposed to the 3.2 GHz) mitigate the difference between the i5 and the i7. I'm guessing not much as I'm assuming it's the multithreading of the i7 that really makes the difference.

    I'm of course going to wait to see what this year's iMac offering looks like before making any purchases (if it comes in Rose Gold, all bets are off, of course *wink*), but I'd like to know what you guys think of this.

    Thanks
     
  2. joema2, Mar 25, 2016
    Last edited: Mar 25, 2016

    joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #2
    I thought the 2014 iMac 27 CPU choices were a Haswell 3.5Ghz i5-4690 or 4Ghz i7-4790K. The 2015 iMac 27 i5 choices are Skylake 3.2Ghz i5-6500 3.3Ghz i5-6600.

    Clock-for-clock, Skylake is probably about 7% faster than Haswell. If you are talking about a 2014 iMac 27 with 4Ghz i7 vs a 2015 iMac 27 with a 3.2 or 3.3Ghz i5, from clock speed alone the i7 would be about 21-25% faster. Subtract about 7% for the i5 Skylake advantage. The i7 has a hyperthreading advantage in highly specific circumstances, but in general you won't see a huge difference.

    You would probably be happy with either one. I've tested the hyperthreading feature on my 2013 and 2015 iMac 27 using a special utility (CPUSetter) to disable it. The benefit of the i7 hyperthreading is highly variable. When exporting from FCP X it's about 30% faster. It does nothing for Lightroom import/export. I haven't closely examined what Photoshop tasks it might help on.

    Aside from possible the i7 vs i5 thermal differences, this area was improved on the i7 models between 2014 and 2015. In general I'd slightly recommend the 2015 i5 model simply because it's newer and you are unlikely to see a significant performance difference from hyperthreading given your workload. OTOH if the 2014 i7 was really 4Ghz, that is approx 18-20% faster than the i5 from clock speed alone. That is enough to notice a difference. OTOH when I use my wife's 2012 iMac with 3.2Ghz i7, it doesn't feel slow.

    If I am mistaken about the 2014 i7 speed and there was a 3.3Ghz i7, then no question get the 2015 i5. If the 2014 you're considering is actually 4Ghz, then consider whether 18-20% CPU speed is worthwhile. This doesn't mean your tasks run that much faster, just the CPU portion. Either one would probably be fine. I doubt you'd see any thermal reliability issues from a 2014 4Ghz i7.

    Make sure you get one with a retina screen. While there are sometimes some good deals on a 2013 non-retina iMac 27, the screen just isn't as good. Counter-intuitively, this makes a bigger difference for text than for graphics.
     
  3. sasha.danielle thread starter macrumors regular

    Joined:
    Mar 15, 2015
    #3
    My apologies if I created some confusion. I was projecting to fall when the 2015 units will likely become the previous generation to 2016 units I assume will come out October-ish, which is why I was ascribing these GHz specs, and I think my own thinking was also a little muddled there.

    Thanks for the feedback though; it's helpful. After thinking about it the afternoon though, I think I'm starting to lean towards the i7 on a new machine. It's $200+ edu pricing, and that really seems like not a lot for getting maybe another year or two out of it. If the money is tight, I might just nab a 256gb instead of a 512gb ssd. This is all pie in the sky until we see what comes out. Still, I like to get some of the decision making determined in advance, rather than get really excited and make rash decisions when the machines are announced.
     
  4. CWallace macrumors 603

    CWallace

    Joined:
    Aug 17, 2007
    Location:
    Seattle, WA
    #4
    Yes, the top i7 for 2014 was a 4790K. And the top i7 for 2015 is the i7-6700K.
     
  5. ApfelKuchen macrumors 68030

    Joined:
    Aug 28, 2012
    Location:
    Between the coasts
    #5
    The feature that really distinguishes i7 from i5 is hyper threading. That's a software-dependent feature - either the OS/app uses it, or not. I'm not aware of any kind of trend in software development that suggests a move to greater use of hyper threading. Pretty much, the types of apps that use hyper threading today used it yesterday. OS X has been using it for years. So, it's not so much about future-proofing, but the kind of performance you can expect from it today.
     
  6. sasha.danielle, Mar 25, 2016
    Last edited: Mar 25, 2016

    sasha.danielle thread starter macrumors regular

    Joined:
    Mar 15, 2015
    #6
    I see, so the benefits it gives me now, will generally be the same 5 years from now? The i7 then won't improve the longevity of the machine, but will generally improve my experience with the machine throughout that time so long as my usage is such that it benefits from hyper threading.

    I guess my question, then, is: How much does general usage, browsing, word processing, and sound recording benefit from hyper threading?

    I should say also that the Pages and Word documents I use can be several hundred pages long. They can also contain 1000s of tracked changes and comments. I've noticed on my retina Macbook, which is admittedly a very different kind of machine from the iMac, that the tracked changes can bog down my rMB's processor. Part of me needing a desktop is that I need a machine more capable of handling these kinds of documents, both for clients (I do freelance editing) and for my own works. Will the i7/hyper threading help me here much, or am I just as well to go with the i5?
     
  7. ApfelKuchen macrumors 68030

    Joined:
    Aug 28, 2012
    Location:
    Between the coasts
    #7
    While there may be isolated instances where you might benefit from hyper threading, (many open browser windows/tabs, perhaps), most of your usage does not. Check with the maker(s) of your sound recording app(s) - hyper threading is used when multiple tasks can be executed simultaneously. Most of what you do is more linear in nature - one thing after another (updating one item triggers the updating of the next). You may have very large open documents, but very little is done to them at any given moment. RAM is likely to be more important than the number of processor cores.

    Note that hyper threading is a method for stretching the performance of a processor core - it really doesn't come into the fore until you've exhausted the number of cores in your processor. Many apps don't use more than a single core, so they wouldn't take advantage of hyper threading. All things being equal, having a two-core processor that hyper threads will be less effective than having a four-core processor that does not have to hyper thread.
     
  8. sasha.danielle thread starter macrumors regular

    Joined:
    Mar 15, 2015
  9. I7guy macrumors G5

    Joined:
    Nov 30, 2013
    Location:
    Looking at Central Park@550 feet
    #9
    Depending on the implementation of the program a two core hyperthreading cpu can have very good performance as long as the two threads are not competing for the same resources. https://en.wikipedia.org/wiki/Hyper-threading
     
  10. sasha.danielle thread starter macrumors regular

    Joined:
    Mar 15, 2015
    #10
    I tend to work with many things open at the same time: browsers with lots of tabs, dictionary, multiple documents in different applications, torrents, mail, messages, iTunes, etc. Will the i7 make a difference here?
     
  11. briloronmacrumo macrumors 6502

    briloronmacrumo

    Joined:
    Jan 25, 2008
    Location:
    USA
    #11
    If "bog down" means a visible spinning beachball cursor while the Word document is loading, it's possible Word/Pages is not taking advantage of background threads ( also known by the marketing name "Grand Central Dispatch" in the Apple world ); this problem will persist regardless of i5/i7 simply because the app isn't designed for better user performance. One key, as mentioned by other posters, is to investigate the apps you use and find out if they are designed to use background threads. Many apps do and others do not. Its implementation depends on many factors such as developer skills, time and its use isn't limited to known high-end CPU hogs. Figuring out ( assuming the developer doesn't disclose it ) if an app is designed for background threads is possible but patience and developer skill/tools are required ( although watching in Activity Monitor might give you some clue ). An Apple store visit might shed some light: launch Word on their machine ( possibly you can make your doc available via the web and open it on the store machine ). Good luck
     
  12. sasha.danielle, Mar 25, 2016
    Last edited: Mar 25, 2016

    sasha.danielle thread starter macrumors regular

    Joined:
    Mar 15, 2015
    #12
    That's a really good idea: to try my documents on their in-store machines.

    I've seen the beach ball in MS Word. I'm not sure I've seen it in Pages (Pages is my primary word processor). What I definitely see in Pages is a massive delay between when I press a key and when it shows up on screen. This becomes noticeable around 400 tracked changes in a document and renders the document unusable around 1000 tracked changes (At this point I have to accept or reject my changes to return the app to functionality). This has never affected the performance of other apps running at the same time.

    EDIT: I should say also that this lag was much much worse before El Capitan, and also in the early betas of El Capitan. I nearly returned the machine. It was horrendous. I banked on El Capitan improving the situation and it did, though not fully, obviously.
     
  13. Dreadnought macrumors 68020

    Dreadnought

    Joined:
    Jul 22, 2002
    Location:
    Almere, The Netherlands
    #13
    As always with getting a (new) Mac or any pc, don't underestimate the gpu. Keep the cpu and gpu in balance. Don't get the entry level gpu, this will slow your mac down, especially in a few years when everything is more graphical.

    The i5 would probably suit you fine, an i7 can really help with soundrecording, depending on the programs you use and how much tracks you record simultaneously.
    You're already getting the ssd, so that's already good. A normal HD is really slow and will impact performance.
     
  14. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #14
    There are no "hyper-threaded apps" per se. Rather there are only multi-threaded apps, which may or may not benefit from hyperthreading. In general the programmer has little control over this. There is no hyperthreading API or special instruction set like with Quick Sync or AVX instructions. It just happens or doesn't -- totally up to the CPU.

    Most apps are heavily multithreaded. Just opening Safari produces about 24 threads. However this does not automatically mean a hyper-threaded CPU will speed up Safari, since most of those threads are not in a runnable state, but waiting on I/O, or a synchronization event. However any app with multiple threads in a runnable state are potential candidates for hyper-threading.

    The OS X thread dispatcher is hyper-thread aware and will often schedule a thread per physical core (rather than a thread per logical core) if it judges that more efficient. This is to reduce cache thrashing, and can be seen in Activity Monitor when every other logical core is scheduled.

    While there are no "hyper-threaded apps" per se, developers can use various techniques to make their apps better behave on a hyper-threaded CPU. Intel has guidelines on this in their whitepaper "Developing Multithreaded Applications: A Platform Consistent Approach": https://www.google.com/url?sa=t&rct...=_PNWoHGsa3skn-LpZN2Ndg&bvm=bv.83339334,d.eXY

    You would be happy with either the 2015 i5 iMac 27 or the 2014 i7 iMac 27. The retina screen was slightly improved in 2015 from a color standpoint. The 2014 4Ghz i7 is probably 18% faster from a CPU standpoint (not considering hyperthreading). Other factors such as hard drive configuration and GPU are also important. E.g, I wouldn't get an iMac with a plain spinning hard drive which was not either Fusion or SSD.
     
  15. sasha.danielle thread starter macrumors regular

    Joined:
    Mar 15, 2015
    #15
    I was going to go with the mid-level GPU. Do you think this will be the weak link in the machine 5 years from now? I thought it would be sufficient, but maybe I'm wrong. I have no interest in gaming or anything but minor video and photo editing. And yes, either a 256 or 512gb SSD. Even with the fusion drive, I don't like the idea of moving parts for longevity. The normal HD is not even in my realm of possibilities.
     
  16. makrom macrumors regular

    Joined:
    Nov 4, 2015
    #16
    Hyper threading is much more about threads rather than tasks. Obviously multiple CPU taxing tasks benefit as well, since each task has at least one thread. But it is of much more significance what kind of application one is using. There'S no benefit from HT when using up to 4 single threading applications.
    These days, well written applications create many threads for CPU heavy tasks, but there are still a ton of programs out there that use multi threading poorly or not at all.
     
  17. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #17
    The R9 M395 is pretty good. See spreadsheet with perf. tests we did in this post: http://forums.macrumors.com/threads...e-2013-imac-and-a-2015.1957498/#post-22594734

    As a video editor I always get the fastest CPU but for general purpose use the M395 is OK. If you mean the M390 I don't have numbers on that. You would be happy with either imac. They are both great machines. The #1 thing is the retina display, and avoid a non-Fusion spinning drive, which you've already decided on.
     
  18. sasha.danielle, Mar 26, 2016
    Last edited: Mar 26, 2016

    sasha.danielle thread starter macrumors regular

    Joined:
    Mar 15, 2015
    #18
    So, I opened a document that was bogging down my Mac in both Word and Pages. I took a screen shot of CPU usage and also RAM usage. The first shot shows memory usage while using Word; the second shows CPU usage. The third shot is of CPU usage while using Pages. I didn't take another shot of memory usage while using Pages because RAM usage didn't fluctuate at all while the machine became bogged down while using either Pages or Word. CPU usage went up for both though--up to 80% with Word and 100% with Pages--in moments where my typing was completely bogging down the application (and by this I mean a huge lag between when I typed something and when it appeared on the screen. Again this doesn't seem to affect other applications running.

    Remember, again, this is on rMB, so a very different scenario, but I'd like to figure out where my usage is most taxing my system so I can make sure I'm amply supported with my iMac.

    Does this seem like something for an i5?
     

    Attached Files:

  19. sasha.danielle thread starter macrumors regular

    Joined:
    Mar 15, 2015
    #19
    Sorry, I meant the M390. I should have been more specific.
     
  20. aevan macrumors 68020

    aevan

    Joined:
    Feb 5, 2015
    Location:
    Serbia
    #20
    I would probably choose the i5 (2015) iMac 5K. The performance will be roughly the same and I strongly believe both computers will work equally for your needs in 5 years time. But the newer one gets newer peripherals (the new keyboard and mouse) and the new DCI P3 screen with better colors. Also, not sure how noticeable is this, but the newer iMac has faster Fusion Drive/SSD speeds.

    You won't see the performance difference between the two computers in real life, but you will see slightly better colors and the new keyboard is quite better in my opinion.

    Just make sure you get either the larger Fusion Drive (in 2015 models, the 1Tb Fusion Drive has a smaller SSD portion, so choose the 2Tb one) or an SSD.
    --- Post Merged, Mar 27, 2016 ---
    Whatever you do in Pages, you will not see any difference between the i5 and the i7. I don't think Pages uses more than 4 threads, if that much. I'm not sure why your computer is bogged down, it could be the RAM, it could be something else entirely. But the difference between an i5 and an i7 is noticeable in multi-threaded apps that use more than 4 threads, and these are mainly rendering apps and video editing apps.
     
  21. sasha.danielle thread starter macrumors regular

    Joined:
    Mar 15, 2015
    #21
    That's fair.
     
  22. jerwin, Mar 28, 2016
    Last edited: Mar 28, 2016

    jerwin macrumors 68000

    Joined:
    Jun 13, 2015
    #22

    Hmm. A lot of compressed memory on that macbook. Now, Apple argues that compressed memory is far superior to the alternative-- swapping to disc-- but it does take CPU cycles to manage.

    You could also look at Console.app and see how many bugs are flitting by, but interpreting these logs requires some experience.
     
  23. sasha.danielle thread starter macrumors regular

    Joined:
    Mar 15, 2015
  24. jerwin macrumors 68000

    Joined:
    Jun 13, 2015
    #24
    Could be. I have an i5 imac 5k, and my machine never feels slow to me. My OCR reader s slow, but that generally runs in the background.

    One benefit the of the 5k imac is that it's great for working with historical documents-- provided the scans are high enough resolution.

    (imac 2014, 5k, i5, m290x, 24 GB memory)
     
  25. sasha.danielle thread starter macrumors regular

    Joined:
    Mar 15, 2015
    #25
    I'll try that. What do you mean by bugs though? This problem is evident even after a fresh reinstall as well.
     

Share This Page