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Heat difference between CPU & Heatsink?
  • Yokemate of Keyboards
    Yokemate of Keyboards
    amigadave
    Posts: 2795 from 2006/3/21
    From: Northern Calif...
    I know this is not MorphOS related, but thought that some of you might be familiar with CPU upgrades and heat problems of overclocking.

    I have not overclocked anything, but I did just do a CPU upgrade on my 1.66GHz Core Duo Intel powered MacMini to a 2.33GHz Core2Duo CPU.

    I used Arctic Silver thermal transfer paste (the good stuff) and I was able to do the CPU upgrade without removing the Heatsink sensor, so I am sure it is still working correctly, but my question is about the heat readings that I am now seeing using the "iStat" widget.

    Right now as I type this message with only Firefox running on my MacMini, I am seeing an average CPU temp of 80 degrees Celsius, while the Heatsink is only 54 degrees Celsius.

    I have seen the CPU temperature rise to 100 degrees Celsius and that seems way too high, so I am wondering if my Heatsink needs to be removed and the Arctic Silver needs to be re-applied? I broke one of the plastic pins with springs and barbs that attaches the Heatsink to the motherboard and holds it against the CPU, but I replaced it with a bolt that fit well.

    It just seems that the heat difference is too much between the Heatsink and the CPU readings that iStat is showing me, and also that my CPU should not be getting that hot.

    I have not experienced any lockups while running MacOSX 10.6.8 Snow Leopard, but I am worried that there might be something wrong with the CPU upgrade and don't want to burn up the MacMini and damage anything.

    Anyone have any ideas, or comments?
    MorphOS - The best Next Gen Amiga choice.
  • »28.07.12 - 18:48
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  • Yokemate of Keyboards
    Yokemate of Keyboards
    amigadave
    Posts: 2795 from 2006/3/21
    From: Northern Calif...
    I think I found my own answer:

    Quote:

    Thermodinamically speaking, I don't think the difference between the temperatures is a good parameter to measure the efficiency of the heatsink (and thermal paste) because temp exchange between cpu and heat sink is by conduction while heat sink x ambient is by convection. These are 2 different processes with different speeds and variables.

    If you have a very big difference between both, this can only prove that your cooling is very efficient and that conduction between cpu and heat sink will be improved because it's driven by the temp difference of the surfaces in contact. If the diffence is too small, conduction will be low and your cooling is not sufficient. None of the cases mean your thermal paste is not good anymore.

    The only thing that will say you need to check the thermal paste is when there is a reasonable (or big) difference (effective cooling) and the CPU temp still increase.


    So, as long as my CPU stays within limits for that model of CPU, then I am okay. If it continues to rise to 100 degrees Celsius, and that temperature seems to be accurate, then I will probably need to recheck my heatsimk installation to make sure it is correctly installed so it can work properly to cool the newly installed Core2Duo CPU.

    [ Edited by amigadave 28.07.2012 - 14:21 ]
    MorphOS - The best Next Gen Amiga choice.
  • »28.07.12 - 20:18
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  • Yokemate of Keyboards
    Yokemate of Keyboards
    amigadave
    Posts: 2795 from 2006/3/21
    From: Northern Calif...
    Looking at these specifications:

    http://ark.intel.com/products/27257/Intel-Core2-Duo-Processor-T7600-%284M-Cache-2_33-GHz-667-MHz-FSB%29

    It appears that the maximum temperature of my newly installed CPU is 100 degrees Celsius, so maybe I am okay with it running between 68 and 85 degrees Celsius most of the time.

    Unless I am reading the specifications wrong?
    MorphOS - The best Next Gen Amiga choice.
  • »28.07.12 - 20:34
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  • Priest of the Order of the Butterfly
    Priest of the Order of the Butterfly
    Doffo
    Posts: 508 from 2010/10/14
    From: Nevada
    Honestly I think you shouldn't be running that hot.. I know the Mac Mini is a tiny computer, but it should at least be able to keep cooler temps.. My brother's I7 idles at 32 celcius and under load gets near 45 celcius.. If the temperatures are that hot while you are idling, something just seems wrong.

    figured even with some bad cooling, id keep it under 50 celcius. Maybe if you can run that mac mini without the top case and power it up, then see how hot things get?
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  • »28.07.12 - 21:04
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