i5 vs i7 and fan noise

Discussion in 'iMac' started by d94ka, Jan 21, 2016.

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  1. d94ka macrumors newbie

    Joined:
    Dec 20, 2014
    #1
    Hi all,

    I'm going to buy a 27" iMac, with the M395 graphics option, but I can't decide if I want the i5 or the i7 processor. I was set on the i5 but it appears that the real world performance difference between i5 and i7 is a little bit bigger than I thought, so now I'm leaning towards the i7. However -- I need my computer to be as quiet as possible and in CPU tests it seems the i7 gets a lot warmer than the i5 under load. Does anyone have any insight into whether or not that heat difference translates into the i7 machines being noisier (and getting noisy faster), than the i5 ones?

    Can anyone who has experience with both machines comment on any fan noise differences?

    Kristofer
     
  2. maflynn Moderator

    maflynn

    Staff Member

    Joined:
    May 3, 2009
    Location:
    Boston
    #2
    I can only comment on the i5, and that model is whisper quiet.
     
  3. tjwilliams25 macrumors 6502

    Joined:
    Aug 10, 2014
    Location:
    Montana
    #3
    You can definitely notice a difference when the i7 is under load in the 5k iMac, but the fan noise is nowhere near any other computer I've had, including a slightly older iMac. I can say, though, that ambient temperature plays a large role as during the last couple of months I haven't noticed it as much.
     
  4. ScorpionT16 macrumors member

    Joined:
    Dec 1, 2015
    Location:
    Toronto, Canada
    #4
    I have an i7 Late 2015 5K with the M390. Its relatively quiet, when gaming under heavy loads it may get louder, but even then no where near my Core i5 Dell PC at work, which sounds like a plane taking off. The new skylakes are slightly cooler, and more threads and cores generally means more performance which results in more heat. Physics is physics.
     
  5. Daisy81 Suspended

    Daisy81

    Joined:
    Dec 29, 2015
    Location:
    Virginia
    #5
    While playing Civilization 5 and having a bunch of other programs open in the background my fan kicks up a little bit on my late 2015 iMac i7 with the 395X. According to Temperature Gauge my fan is going 2147RPM with an average RPM of 2111RPM. The perceived noise on my end is that it is a little over a whisper but not bothersome. In fact with my Logitech G930 headphones I can barely hear the fans at all even with the volume level one notch above mute.
     
  6. iemcj macrumors 6502

    iemcj

    Joined:
    Oct 31, 2015
    #6
    The fan itself is the exact same in both. The i7 is capable of "doing more work" than the i5 so it can thus take on a higher max load.

    If you're in a task that is only using half the i5s power, it'll be really cool, and that same task will only be using like 1 quarter of the max power of the i7 so it'll also be running cool.

    If you're in a task that is maxing the i5, it's not going to be pushing the i7 to it's limit and in that situation the i7 is going to be running cooler.

    If you're at a task that is beyond what the i5 can do, it'll be still pushed to it's limit and making it's max heat. The i7 has a higher maximum it can do so if you push THAT one all the way, yes it will be hotter and thus the fan will need to run maybe a few hundred rpm faster. But for day to day tasks you're not going to be having your cpu at max load for sustained times, maybe for a few seconds here and there but that's it. Gaming doesn't stress cpus that hard so it'll be the same there.

    The ONLY time i've actually heard cpu fan noise was when converting some mkv files to mp4 so I could edit them in imovie. But even then it wasn't LOUD at all, trust me, I grew up with noisy desktop computers and laptops and this thing even at 100% core usage for 20 minutes is barely louder than my macbook pro when it's hot haha
     
  7. cynics macrumors G4

    Joined:
    Jan 8, 2012
    #7
    I've noticed the difference in sound is noticeable when comparing the Haswell i5 to i7. Its very difficult to get the fan to lift off idle speed with the i5 even while doing video encoding. However its not as fast....

    For people the only time I could measure a difference would be while doing a very long video encode and typically I'm not actively waiting for that to complete since it can talk multiple hours so I don't notice the difference.
     
  8. Daisy81 Suspended

    Daisy81

    Joined:
    Dec 29, 2015
    Location:
    Virginia
    #8
    Thankfully while the late 2015 iMac is more likely to crank the fan up it is not as prone to throttling the processor while doing things like encoding video. :D Check out this video on youtube.
     
  9. killhippie, Jan 23, 2016
    Last edited: Jan 23, 2016

    killhippie macrumors regular

    killhippie

    Joined:
    Jan 12, 2016
    Location:
    UK
    #9
    I have an almost maxed out 5k imac, i7, M395X, 1TB SSD and 16GB ram, and its very quite, quieter than my friends 2014 model which throttled a lot. The 2015 keeps temps very low indeed.
     
  10. maflynn Moderator

    maflynn

    Staff Member

    Joined:
    May 3, 2009
    Location:
    Boston
    #10
    From the reviews that I've read the 2015 5k iMac runs much cooler then its predecessor, and is less likely to need to ramp the fans up. My i5 seems to back that assessment up, I usually only see 35c in iStat Menus.
     
  11. AlexisV macrumors 68000

    AlexisV

    Joined:
    Mar 12, 2007
    Location:
    Manchester, UK
    #11
    Virtually silent under normal use.

    Slight whirr under load. That's it.
     

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