G5 Quad: Core Temperature Disparity

Discussion in 'PowerPC Macs' started by tevion5, Aug 16, 2015.

  1. tevion5, Aug 16, 2015
    Last edited: Aug 16, 2015

    tevion5 macrumors 68000

    tevion5

    Joined:
    Jul 12, 2011
    Location:
    Ireland
    #1
    Being relatively new to my Quad, I have yet to learn EVERYTHING about it, although my enthusiasm for the machine has helped. I've added a second HDD, two 7800GT's, Leopard and Tiger, as well as multiple games and software packages. One of these included temperature monitor which I like to put in my menu, vainly displaying the temps of all four cores. I also used Onyx to install the Processor system preference panel, which is very cool indeed.

    But one thing has been bugging me lately about my core temperature. Namely, core 2 (aka. Core B on Chip 1) always seems to be more than 20*C higher than other cores during direct usage, and around 10*C higher on idle. Most cores go up to 50*C or so, but core 2 flys up as far as 75*C. In fact I sometimes wonder when my fans burst into life, that if they are only doing so for that one damn core.

    An idea of what I mean:

    Core Temp Dis.jpg


    Do any Quad owners here have the same story? Is this normal?
     
  2. Intell macrumors P6

    Intell

    Joined:
    Jan 24, 2010
    Location:
    Inside
    #2
    One processor or core being higher than the others is somewhat normal on G5's, more common on liquid cooled models in particular. As the cooler coolant comes out the radiator, it goes into the first processor. It then goes into the second processor, while still having the first processor's heat in it. After the second processor, it moves to the radiator to start the process over again.
     
  3. tevion5 thread starter macrumors 68000

    tevion5

    Joined:
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    #3
    I suppose that makes sense alright. Just thought it strange when there is such a difference between two cores of the same chip.
     
  4. jbarley macrumors 68030

    jbarley

    Joined:
    Jul 1, 2006
    Location:
    Vancouver Island
    #4
    I have a G5 quad and my core temperatures also are always different by 10 or 15 degrees C, have been that way since I purchased it 3 years ago with no apparent problematic issues.
     
  5. Mnowell69 macrumors regular

    Mnowell69

    Joined:
    Jul 4, 2013
    Location:
    Bedford, UK
    #5
    ..but what the OP is saying is that only 1 of his cores is way out, not one of his processors (as is always the case with QUADS). i do find this very strange and it could be down to a problem with whatever sensor reads the temperature on core 2. (no idea if it's part of the logic board or part of the processor)
     
  6. MagicBoy macrumors 68040

    MagicBoy

    Joined:
    May 28, 2006
    Location:
    Manchester, UK
    #6
    It's an on-die sensor on the 970MP. Odds are it's probably an iffy sensor.
     
  7. tevion5 thread starter macrumors 68000

    tevion5

    Joined:
    Jul 12, 2011
    Location:
    Ireland
    #7
    If that is the case, then my fans are spinning up for no reason then. Just a bit annoying, but the high temps probably aren't true do no real damage is being done.
     
  8. LAHegarty macrumors member

    LAHegarty

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    Aug 17, 2013
    Location:
    York, UK.
    #8
    Name of software?

     
  9. eyoungren macrumors P6

    eyoungren

    Joined:
    Aug 31, 2011
    Location:
    Phoenix • 85037
    #9
    Either Temperature Monitors X (or Lite) or iStat Menus.

    iStat Menus displays data in your menu bar. Version 2 is the last "free" version, but it has a memory leak with the clock (when additional clocks are added) that wasn't fixed until version 3.0 which is a paid version and Intel only.

    Version 4 is the current version of iStats.

    I have 1 and 2 and I can zip up Temperature Monitor if you want either of those.
     
  10. jbarley macrumors 68030

    jbarley

    Joined:
    Jul 1, 2006
    Location:
    Vancouver Island
    #10
    Paid version yes, but there is a PPC version as you can see below.

    Picture 1.JPG
     
  11. eyoungren macrumors P6

    eyoungren

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    Phoenix • 85037
    #11
    Thank you James! Forgot about that.
     
  12. LAHegarty macrumors member

    LAHegarty

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    Aug 17, 2013
    Location:
    York, UK.
  13. amagichnich macrumors regular

    amagichnich

    Joined:
    Feb 3, 2017
    Location:
    Cottbus, Germany
    #13
    It doesn't necessarily have to be a sensor error. On multicore systems one core is usually one 'primary' core (as seen by applications that can't make use of multiple cores) that's usually hotter than the rest.
    The biggest difference I have seen on one of my windows machines was 17°C!
    I don't have G5 and therefore can't proof that the same applies to G5 Macs
     
  14. Orizence macrumors 6502

    Joined:
    Nov 10, 2014
    #14
    On my DC 2.0 It always has a 7-8c difference between cores, it always seems to be like that.
     
  15. amagichnich macrumors regular

    amagichnich

    Joined:
    Feb 3, 2017
    Location:
    Cottbus, Germany
    #15
    But... 43 to 68 seems to be a bit much. Does anyone know how the cores are assigned in G5s? From the temps I assume core 1 and 3 are CPU1 and 2 and 4 are CPU2 - is that correct?
     

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