15" 2014 2.2 vs 2.8

Discussion in 'MacBook Pro' started by grame, Aug 12, 2014.

  1. grame macrumors member

    Joined:
    Nov 12, 2007
    #1
    I have both at the moment - the base 2.2 Iris Pro and the 2.8 with the 750m. Decided to stick with the base model and return the 2.8. I never play games or do hefty video work so the Iris Pro is fine. The 2.8 runs hotter and the fans are more noticeable. Geekbenched them both - 13100 v 14500, which is actually pretty good for the 2.2. The only downside is the smaller SSD - but I'll get one of those 128GB SD cards from Transcend to open it up a bit until third-party options appear. I guess the point I am making is the base model is pretty fab value for what you get and what you pay - and certainly none too shabby when run alongside the top end model.
     
  2. alphaod macrumors Core

    alphaod

    Joined:
    Feb 9, 2008
    Location:
    NYC
    #2
    I think the top end model runs hotter mostly because it's got the dGPU which adds more stress to the system.

    Then again you could have variations of thermal paste application between computers, so that would affect things as well.
     
  3. maflynn Moderator

    maflynn

    Staff Member

    Joined:
    May 3, 2009
    Location:
    Boston
    #3
    A number of factors could be contributing to the heat, though I do suspect its the dGPU.

    I think the base model is a great machine and there's no reason to go to the top tier machine based on what you posted.
     
  4. The Mercurian macrumors 65816

    Joined:
    Mar 17, 2012
    #4
    Surely the extra 600MhZ is a factor too ? I mean if not why not just jack it up to 4GHz ?
     
  5. maflynn Moderator

    maflynn

    Staff Member

    Joined:
    May 3, 2009
    Location:
    Boston
    #5
    It is a factor, but the Megahertz wars are over and at this point Intel is increasing performance in other ways. bumping up the speed from 2.2 to 2.4 will give you a small boost, but I don't think in real world activities it will be that noticeable.
     
  6. SarcasticJoe macrumors 6502a

    SarcasticJoe

    Joined:
    Nov 5, 2013
    Location:
    Finland
    #6
    Probably because if you did that, the CPU would run much hotter and under stress it would probably get so hot it'd practically selfdestruct.

    Sure, higher clocks do give it a bit more performance, but it's not as drastic as the relative clock frequency increase would indicate. There's a lot of other factors that make up the performance of the CPU and not all of them are affected by the clock frequency going up.
     
  7. The Mercurian macrumors 65816

    Joined:
    Mar 17, 2012
    #7
    Some of us still want/need faster clock speeds unfortunately :(

     
  8. SarcasticJoe macrumors 6502a

    SarcasticJoe

    Joined:
    Nov 5, 2013
    Location:
    Finland
    #8
    I don't think a few hundred MHz does add much, or any, heat. Intel CPU's generally have quite a lot of frequency moving room before you need to start upping the voltage. Having this kind of moving room is the reason why a lot of PC enthusiasts used to lower the voltage on their CPU's to get lower temperatures and power consumption without losing any performance. The identical TDP (which is basically the heat production under maximum stress) figures would indicate that the two CPU's run at the same voltage.

    With 4 GHz, they would obviously have to significantly up the voltage and this would also increase the heat produced across the board.
     
  9. yjchua95 macrumors 604

    Joined:
    Apr 23, 2011
    Location:
    GVA, KUL, MEL (current), ZQN
    #9
    In heavy tasks, such as Macoh stress tests, the 750M model actually runs cooler.

    This is because tasks are spread over two chips instead of just a single chip.

    In the Macoh stress tests, the Iris Pro model experienced throttling shortly into the test. The 750M variant did not throttle at all and ran cooler.

    The myth that the dGPU model runs hotter has to die. The dGPU can be disabled with gfxcardstatus.
     

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