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  1. #1


    Member Since
    Feb 19, 2009
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    Question Very hot CPU temps
    I've noticed (only today) that my macbook (13" unibody '08 model) is running very hot.

    iStat is recording the CPU temp and Heatsink A temps at around 80-90 degrees C (not F, but C). This seems insanely high, and it's not even under load. The back part of the macbook feels very hot to touch; there's no fan noise (ive never heard fan noise actually, is this right?).

    Been fine since I bought it, but today have really noticed the temps. As I say it's not even doing anything intensive; right now im just writng this message in firefox and the CPU is running at at 72 degrees C.

    Another odd thing. iStat is saying that the 'user' is using 50% CPU ... whereas Activity monitor is reporting about 3% usage. As the CPU is running so hot im inclined to believe iStat ... but then there's nothing running that should be eating that kind of CPU.

    Anyway, are these normal numbers??

    N

  2. #2

    D3v1L80Y's Avatar
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  3. #3

    vansmith's Avatar
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    No they are not.

    I usually run in the mid 40's. At the end of the day, if my MB has been on all day, it might average out at about 50. The highest I have seen it go was 80 and it came down from that pretty quickly and that was only when I was encoding some video so CPU usage was just about maxed. Encoding usually gets the CPU temp to average out at about 70-72. Once its done, its drops quickly back to about mid 40's.

    If that is how hot your CPU is, your fan should be going like crazy. If it's not going, its probably broken and why your CPU is running hot. I would have it looked at right away.

    EDIT: Try blowing out the fans with some compressed air. If you fans aren't moving at all, this probably won't help but it's worth a shot.
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  4. #4

    D3v1L80Y's Avatar
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    Quote Originally Posted by vansmith View Post
    If that is how hot your CPU is, your fan should be going like crazy. If it's not going, its probably broken and why your CPU is running hot. I would have it looked at right away.
    Or it could just be that iStat is way off... as is the norm for iStat.

    Quote Originally Posted by mrnathan View Post
    Another odd thing. iStat is saying that the 'user' is using 50% CPU ... whereas Activity monitor is reporting about 3% usage. As the CPU is running so hot im inclined to believe iStat ... but then there's nothing running that should be eating that kind of CPU.

    Anyway, are these normal numbers??
    Normal? Yes, because iStat is entirely unreliable.

    Don't worry about iStat or any other third-party monitors for your system.
    Paying attention to them will only make you neurotic.
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  5. #5


    Member Since
    Feb 19, 2009
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    hotness
    I restarted and the 50% CPU hog mystery has gone and the temps are now around 45 degrees C, which seems more reasonable. The fan is showing as 2002rpm (no noise at all though .. never had the fan once .. is it just uber quiet? not sure what the point of a fan is when there's no obvious exhaust point :p)

    Should I ever hear the fan? 2002rpm seems fast enough to hear to me. All this is reported by iStat btw

    Thnaks for the links, they were of some help

    What does it mean when it says user % is 50% CPU load, and system is 2%. The '50%' doesnt show in the list though (in activity monitor), so no idea what was causing it :s

    Also i know a 3rd party software cant be fully trsuted, but the backend bottom and top of the macbook unibody felt very hot, so I believed the temp reading, and the 50% load showed as user% in both iStat and the activity monitor.

    as i say, restart seem to fix it though

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