2009 Mac Pro Temperature Question

Discussion in 'Mac Pro' started by Fend0r, Sep 2, 2009.

  1. Fend0r macrumors newbie

    Apr 25, 2009

    Since I ordered my early 2009 octo Mac Pro as soon as it was released and installed Temperature Monitor I recognized that my A CPU gets about 10 - 15 degrees hotter than my B CPU.
    I thought that the OS might not distribute the Processes perfect on all cores, but I still have this "problem" in 10.6. And I think as 10.6 is "optimized" for multiple cores my first thought can't be true.

    Does anyone know the reason?

    I know its not a big problem. But my Mac is running 24/7 so over time I am worried that CPU A might not life as long as CPU B due to the constantly higher temperature...
  2. gugucom macrumors 68020


    May 21, 2009
    Munich, Germany
    Check the internal heat sink fan for rpm. Perhaps the thing is not turning. Also one CPU is behind the air shadow of the other in the 2009. Perhaps that is the hotter one. Finally check the seating of the heat sink and application of thermal paste.
  3. IronFixXxeR macrumors member


    Jun 20, 2009
    Austin, Texas
    10.6 has tools to allow developers to optimize for use of all cores. The apps you are currently using most likely not taking advantage of all the cores yet. So your first thought may be correct.
  4. Tesselator macrumors 601


    Jan 9, 2008
    You can watch the activity monitor to know if it's distribution or not - or how much of it is. Mine does the same thing though. And one core more than another within the same CPU too. It doesn't seem to be related to activity exclusively. On mine one core or CPU just runs hotter than another. I think wiring, thermal paste, the way the HID is fitted, even the slightest tilt of the heat sink all contribute to this.
  5. Fend0r thread starter macrumors newbie

    Apr 25, 2009
    Tesselator your reply is the perfect situation to ask another question i haven't found an answer to yet on google but was too shy to ask for it:

    I have seen screenshots where the Activity Monitor window (not the cpu usage one) shows multiple cores on the cpu pan in the graphical cpu usage pane. Mine shows only general usage and i can't find an option to turn on multiple core usage. Any hints on this?

    So far from your answers it seems to be quite normal with the 2009?

    Another thought was the possibilty of an air shadow brought up by gugucom. But if i look into the mac the CPUs are staggered and just from feeling the air it seems to be "normal" to hit both heat sinks...
    And for checking application of thermal paste I'd have to remove the heatsinks from the CPUs and re-apply them whats a bit of a too risky task for me to do on that machine.

    To IronFixXxeR theory: I am perfectly aware of the situation with applications using multiple cores or not. But as long as applications are multi-threaded the OS takes care of distribution between cores as far as i know... And I am talking about system idle cases.
    So my original thought was that Leopard just didn't handle distribution of Threads (lets not call it Applications anymore for this specific case and obvious reasons) was just not perfect and it will be fixed with 10.6.
    I don't know if I am correct with this thoughts because my System Programming Expierence was before Multi-Core technology and therefore i am not up to date (even on theory) on this.

    As far as checking distribution of work to the cores:
    Even when the System is idle i have a difference of 10-15 degrees between the CPUs

    If you can tell me its "normal" and you can't do anything about it i guess i have to live with it.

    But as you see my conclusions determine that this can't be normal behavior.
  6. Infrared macrumors 68000


    Mar 28, 2007
    How accurate are these thermal sensors in general?
  7. Tesselator macrumors 601


    Jan 9, 2008
    In the "Window" Menu there should be:
    Floating CPU Window,
    CPU History, and
    CPU Usage.​
    All of which will show the separate cores graphed individually.

    I think so. It certainly is for 2006, 2007, and 2008 models. ;)

    Yeah, although considering airflow as best I can mentally model it - it will never be perfectly distributed. It's just how air is. Like the eddies, swirls, and undertows of a river. Air, is like, totally spun dude. :D

    Yeah, for sure this isn't anything that has a solution to it. I mean unless you thousands of hours to invest into it. It's just a condition that often happens and we get to wonder about it. ;) Another set of variables are the accuracies of the sensors themselves and their respective placements. Also every CPU die is slightly different and this also has an affect.

    Yeah, that's right. A "scheduler" which is part of the OS does most or all of this. An idle system usually has between 50 and 200 processes running. In snow leopard hopefully Apple has written or rewritten many of these to use the Grand Central framework and so the OS at idle may be more evenly distributed. Whether they have or not or which ones have been, isn't clear at this time - Apple hasn't said anything specific that I know of on the topic. The scheduler itself has been touched in SL but I dunno exactly what they did and they're not telling us that either AFAIK. It's probably just a slightly different load balancing scheme as schedulers are pretty ancient already and the best optimizations have long ago been realized and implemented. Each new change to a CPU's architecture may offer new opportunities though.

    Yeah, that's pretty normal. Here's mine right now:

    1. 44.0℃/111.2℉ - CPU Core 1
    2. 42.0℃/107.6℉ - CPU Core 2
    3. 45.0℃/113.0℉ - CPU Core 3
    4. 40.0℃/104.0℉ - CPU Core 4
    5. 39.0℃/102.2℉ - CPU Core 5
    6. 38.0℃/100.4℉ - CPU Core 6
    7. 33.0℃/91.4℉ - CPU Core 7
    8. 36.0℃/96.8℉ - CPU Core 8

      This is with the CPU cores all at less than 2% ~ 5% while reading this thread for the past 10min - and CPU cores are VERY responsive in terms of heat and sensor readings. A single core can increase or decrease it's temperature almost as fast as the activity percentage taking place on it

    Yup, it's normal and there's nothing you can feasibly do about it. Honest! :)

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