CPU temperature is 20C more than the CPU Heatsink during heavy loading?

Discussion in 'MacBook Pro' started by crman, Apr 23, 2010.

  1. crman macrumors newbie

    Joined:
    Apr 22, 2010
    #1
    I got my macbook pro core i7 yesterday. I found that the cpu temperature is 20C more than the cpu heatsink. is it a problem of my mbp?:confused: just curious to ask because it is just 2~6 degree Celsius varying in my mac mini.
     

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  2. therealseebs macrumors 65816

    therealseebs

    Joined:
    Apr 14, 2010
    #2
    Haven't seen that yet, but haven't loaded the machine much. It doesn't sound unthinkable, though; cores can get pretty hot.

    But thank you for the reminder that I'd somehow lost iStat Menus in the last year. Went and got it back, all happy again.
     
  3. Pax macrumors 6502a

    Joined:
    Dec 12, 2003
    #3
    Depends on the CPU load....

    If your i7 is idle (say <10% CPU load) the difference should be more like 5 C. At the moment my MBP just has Safari open and the difference is 5 C.

    If your i7 is working hard (near 100% total load or 4x100% for the 4 virtual cores) the difference will be very much like 20 C.

    My 13" 2009 model Core2Duo is 20 C hotter than the heatsink when at 100% CPU. My 2006 CoreDuo Macbook is similar. I've seen others in person with the same difference, also some posters on here have reported almost exactly the same answer.

    If you do the math for the thermal resistance of the silicon substrate, the copper spreader and the thermal paste, you'll come up with a similar number.

    Was your MBP idle?
     
  4. crman thread starter macrumors newbie

    Joined:
    Apr 22, 2010
    #4
    the cpu temperature is abt 40C, heatsink is abt 30C when it's idle.
     
  5. Pax macrumors 6502a

    Joined:
    Dec 12, 2003
    #5
    Sounds about right, my Core2Duo has about 42 C, 35 C. My guess would be your i7 dissipates a bit more heat at idle so there might be a tiny bit of a bigger temperature difference.

    Nothing to worry about, in fact there's nothing you can really do, it's just the physics of pulling 40-plus watts of heat out through an area the size of your fingernail.
     

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