CPU Core 0 30-35 degrees hotter

Discussion in 'Mac Pro' started by RoastingPig, Jun 30, 2013.

  1. macrumors 68000

    RoastingPig

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    #1
    Just a Quick Question im on a 5.1 quad core 2.8 mac pro with istat and im wondering why my CPU Core 0 "runs at 136 degrees at idle" is always 30-35 degrees hotter than CPU A Tdiode wich runs at 98 degrees on idle and CPU Heatsink wich runs at 93 degrees on idle?
     
  2. macrumors 601

    Tesselator

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    #2
    It could be any one or a combination of many things including:

    1. the accuracy of one or more sensors,
    2. the difference in placement of one or more sensors,
    3. the scheduler bias of one CPU over another,
    4. the heat sink fins are dirty in one area more than another,
    5. the thermal paste was applied differently on one or the other,
    6. the airflow volume favors one over the other.
    and so on.

    If I were to guess I would accuse numbers 1, 2, and 6 as being the most responsible - especially number 6. :) And you should be able to tell if it's number 6 I would think... After awhile number 6 will cause a number 4 condition to appear.
     
  3. macrumors 65816

    rabidz7

    #3
    This sounds like it may be thermal paste.
     
  4. thread starter macrumors 68000

    RoastingPig

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    #4
    i still have applecare until september you think i should take it in?
     
  5. RoastingPig, Jun 30, 2013
    Last edited: Jul 1, 2013

    thread starter macrumors 68000

    RoastingPig

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    #5
    Im coming towards the end of my applecare and i want at least one thing to get replaced never had too:)


    [​IMG]

    Here are the readings im getting
     
  6. thread starter macrumors 68000

    RoastingPig

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  7. macrumors 6502

    Studio K

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    #7
    What exactly is the 'CPU0 Relative to...' reading?

    I can't remember what mine is, but I noticed that it goes down as Tdiode rises.

    I mostly pay attention to Temp Diode and individual Cores (readable using Temperature Montior app). I've no idea what this Relative reading is supposed to be. Hopefully someone on the forum has knowledge about this. I'd love to know.
     
  8. macrumors 68030

    pastrychef

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    #8
    Sometimes I see about a 20F difference between CPU A and B. Sometimes A is hotter, sometimes B. I've never had any problems with stability on my Mac Pro.
     
  9. macrumors 6502

    Studio K

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    #9
    I don't know if the 'Relative' reading is to do with 2-processor setups. Mabye it is.
    The OP and I are using single-processor Mac Pros. Yet we still get a temperature reading for this.
     
  10. hfg
    macrumors 68030

    hfg

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    #10
    What might make sense is "xxx Relative to Ambient" ... i.e. the temperature rise of the part over nominal.

    Perhaps the OP can revisit that screen and see if it is possible to pull it wider to get the whole line of text.
     
  11. thread starter macrumors 68000

    RoastingPig

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    #11
    it says CPU A, Core 0 Relative to Prochot
     
  12. hfg
    macrumors 68030

    hfg

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    #12
  13. thread starter macrumors 68000

    RoastingPig

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    #13
  14. hfg
    macrumors 68030

    hfg

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    #14
    Back in the Pentium days it was a CPU pin which would go active on "Processor Hot" ... perhaps Intel still uses that term (and pin) today?

    The extreme temperature you are seeing only on one location, assuming all continues to run OK, sounds like a faulty sensor to me.
     
  15. thread starter macrumors 68000

    RoastingPig

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    #15
    I wonder if that sensor being bad can cause my fans to act all wonky
     
  16. Studio K, Jul 1, 2013
    Last edited: Jul 1, 2013

    macrumors 6502

    Studio K

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    #16
    Perhaps the Relative to ProcHot is the number of Degrees F or C that you are FROM the maximum allowable temperature (TJmax?). My Prochot number DECREASES as my Tdiode increases.
    That would put your T Diode's maximum 'safe' temperature at 234F (or 111C) more or less (91F + 143F). I presume that this is the temperature at which your system would shut itself down to prevent damage from overheating.

    I always understood that anything above 100C was too hot.
    If all of this is the case, then the high number that you see (for Relative to Prochot) is possibly a good thing.

    Try stress-testing the CPU and see what the 'CPUA Relative' temperature does. Open Terminal and type: yes > /dev/null &

    Do several of these until your CPU cores are being heavily utilised.
    To stop the testing, type: killall yes
     
  17. thread starter macrumors 68000

    RoastingPig

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    #17
    When i stress the cpu and the temp rises the prochot goes down. I understand now thats how much more degress the cpu can handle...does anyone else have that feature i have the latest update to istat wich i think is 4.06

     
  18. macrumors 6502

    Studio K

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    #18
    What sort of temperatures did you see in iStat when stressing the cpu?
    What was your CPU T diode? And what was the Relative to....?
     
  19. thread starter macrumors 68000

    RoastingPig

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  20. macrumors 6502

    Studio K

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    #20
    Here are my Cinebench results.
    My temperatures are higher than yours, so I am the one that needs to be concerned.
    You topped out at 60C with no increase in fan speed.
    I only STOPPED at 72C because the CPU fans were going faster. And because the test was short.
     

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  21. macrumors 6502

    Studio K

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    #21
    I am paying close attention to my CPU temps because I've just replaced my W3520 processor with a W3570.
    I am concerned that my choice of thermal paste and/or my method of applying it may be contributing to these higher temperatures.

    I used Noctua NT-H1 paste.

    I would like to see others in the forum who've swapped CPU's in their quad-core Mac Pros post their CPU temps and share their choice of thermal paste.
    I'm beginning to wonder if Apple's thermal grease is particularly optimised to work with their heatsink. And that applying any other random thermal paste will not yield the same quality of cooling.

    ----------

    Is your machine a quad-core? Your sig says 12-core.
    I am a single processor, quad-core. Are you dual-processor?
     
  22. thread starter macrumors 68000

    RoastingPig

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    #22
    I just picked up this quad from a friend on the cheap and intend to flip on a later date..my 12 core is for home use and on the version of istat i have on that machine that reading dosent even show up on the menus
     
  23. macrumors 6502

    Studio K

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    #23
    I notice that all of your temperature readings are lower than mine. Ambient is lower and hard drives are all considerably lower.

    My room termperature is 79-80F. What's it like where you live? Do you live in a cold climate?

    --------
    I can't imagine buying a 2010 Mac Pro 'on the cheap'? Mine's a 2009 I picked up used, but I still wouldn't say it was inexpensive. Just a lot less than it's original new price.
     
  24. thread starter macrumors 68000

    RoastingPig

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    #24
    I got it for 700 ..im in L.A its pretty hot today like 90 but on average like 80 and in my room like 75


     

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