[MB] CoreDuoTemp Strangeness

Discussion in 'Mac Pro' started by Abulia, Jun 5, 2006.

  1. Abulia macrumors 68000

    Abulia

    Joined:
    Jun 22, 2004
    Location:
    Kushiel's Scion
    #1
    I have some strangeness with CoreDuoTemp and my MacBook.

    Essentially, CoreDuoTemp oscillates between reporting two numbers as my MB heats up.

    Now, it's worth mentioning that I did take my MB apart and reapply the thermal paste. This wasn't particularly difficult nor did my MB have what I would consider an "excessive" amount of paste. There was quite a bit around the edges, but the application on the CPU/GPU die looked fine. In any event, reapply I did.

    Afterwards, upon starting up, my temps did seem slightly lower by about 1-2c. After letting the unit warm up and put it under a load -- at around 70ish c -- CoreDuoTemp started to report one number and then a second (lower) number. As the machine heats up under load, the disparity between the two values increase.

    Now, here's what concerns me. Before reapplying my paste my peak temperature was 85c and my sustained load temp was 82c. After reapply my paste CoreDuoTemp reports two numbers, one higher than my "old" temps and one lower. Frankly, I've no idea if my system is running hotter, cooler, or the same as before.

    My original guess was that the heat sink has two temperature sensors on it (it has two connectors at least), one reporting the CPU temp and the other the GPU temp. Those temp sensors on the heat sink, if you take a look on ifixit or tear apart your MB, aren't anywhere near the cores, though; they're on the heat sink on the side of the radiator, less than 1mm apart.

    How two sensors, less than 1mm apart can show a 7c temperature variance I have no idea.

    So, anyone have any ideas?

    My MB runs fine, but now I'm unable to accurately measure my temps. As I said, the new "high" temps are, in fact, higher than my "old" temps, but the second number is lower. My gut says that the MB is running slightly cooler (1c) but the two temps being reported by CoreDuoTemp are kinda freaking me out.

    [Edit] As a matter of example, with both cores on full load (yes > /dev/null) and CoreDuoTemp updating every second, my MB will report a temperature of 87c, one second later a temperature of 80c, one second later 87c, etc, etc.
     
  2. Pressure macrumors 68040

    Pressure

    Joined:
    May 30, 2006
    Location:
    Denmark
    #2
    Try disabling one core and see what it does. Yes, it only displays one temperature. You should download Temperatur Monitor instead, much better. It shows history as well as shows the harddrive temperature.

    I just had two shells open in Terminal running the yes > /dev/null command for an hour and CoreDuoTemp were reporting temperatures between 20-26°C, which clearly is wrong. This is a MacBook Pro and it didn't get that hot, as some are.

    Nice job voiding your warranty immediately ;)
     
  3. Abulia thread starter macrumors 68000

    Abulia

    Joined:
    Jun 22, 2004
    Location:
    Kushiel's Scion
    #3
    Nothing ventured, nothing gained.

    I'll try temp monitor.

    [Edit] How do you disable one core?
     
  4. Pressure macrumors 68040

    Pressure

    Joined:
    May 30, 2006
    Location:
    Denmark
    #4
    Indeed, I didn't really have a heat issue so I found no reason to play with something that could turn into a $2000 brick heh.

    You can download a program called CHUD from Apple Developer Tools page but I also think the program is present on your Mac OSX install disks.

    Once installed, you will under System Preferences see a new option called Processor.
     
  5. Abulia thread starter macrumors 68000

    Abulia

    Joined:
    Jun 22, 2004
    Location:
    Kushiel's Scion
    #5
    Tried Temperature Monitor/speedit and no change. In fact, with both Temperature Monitor and CoreDuoTemp open, they both show the two numbers.

    For example, my CPU temp just went from 89c to 83c in less than a second and then back to 89c.

    My hard drive temp is a constant cool 28c. :)
     
  6. Abulia thread starter macrumors 68000

    Abulia

    Joined:
    Jun 22, 2004
    Location:
    Kushiel's Scion
    #6
    It's a little hard to see, but the up/down lines are the fluctuating temps.
     

    Attached Files:

  7. Pressure macrumors 68040

    Pressure

    Joined:
    May 30, 2006
    Location:
    Denmark
    #7
    Aye when I disable one processor the temperature history just shows a straight line.

    Let me grab a picture of it :)

    Edit:

    [​IMG]

    You can clearly see the point where I disable one processor (the orange line).
     
  8. Abulia thread starter macrumors 68000

    Abulia

    Joined:
    Jun 22, 2004
    Location:
    Kushiel's Scion
    #8
    It looks like you were right...the two temps are the two cores. Why they would have a 5-7c variance I can't say. Any ideas?

    Here's with one core disabled. The results are steady without abnormal fluctuation. Peak was 81c under full load.
     

    Attached Files:

  9. Pressure macrumors 68040

    Pressure

    Joined:
    May 30, 2006
    Location:
    Denmark
    #9
    It can depend on the load variances of the processor cores.

    But really, your guess is as good as mine there :)
     

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