The efficacy of iStat Pro and a couple other fan questions

Discussion in 'iMac' started by thermodynamic, Sep 12, 2009.

  1. thermodynamic Suspended

    thermodynamic

    Joined:
    May 3, 2009
    Location:
    USA
    #1
    Hi again! :) I've been keeping an eye on iStat Pro's temperature and voltage readings.

    Can a CPU use NEGATIVE wattage (e.g. -1.81.W)? :eek:

    It claims I have two northbridges. (there should only be one NB, and a southbridge.) It reports 0 amps being used for both.

    And given the fact that, a manual feel of the rear of the iMac (24", early 2009, running Snow Leopard 10.6.1) was uniform up top, and nowhere near scalding to the touch, is it possible that the temps, amps, watts, and other values are being misread? (or could the heatsink on the NB be poorly mounted, which I'd think is unlikely...)

    Lastly, how fast can the built-in fans get? My CPU fan is running at 2553RPM, HD fan is at 3583RPM, and DVD fan is running at 2717RPM.


    Note: NB1 is currently at 62C, and NB2 is at 49C - I ramped up the CPU fan to 3000RPM. CPU is at 39C. The only other component to begin to approach the temp of the NB is the GPU Diode, at 51C. Ambient room temp is 30C (appx 85F).

    I'm sure my iMac won't fry anytime soon (so far I only do photographic and web site design, some flash/after effects development, but nothing constantly heavy), but even when I used Windows PCs, I aimed to keep all temps as low as possible.

    Thanks again for taking the time to read this post!!
     
  2. Hellhammer Moderator

    Hellhammer

    Staff Member

    Joined:
    Dec 10, 2008
    Location:
    Finland
    #2
    ODD can get up to 4800rpm, HDD 5900rpm and CPU 3600rpm. I think there are two temperature sensors in Northbridge, that's why there are two temperatures.

    Remember that full size tower is different thing than narrowly packed all-in-one computer. Towers have at least three fans, usually more if you have OCd or hot components plus there's more space than in iMac, if your CPU heats up in iMac, the whole computer heats up
     
  3. thermodynamic thread starter Suspended

    thermodynamic

    Joined:
    May 3, 2009
    Location:
    USA
    #3
    I have not overclocked my iMac; never will.

    Though the fact it's the northbridge constantly being 25 degrees warmer than the CPU is arresting. My macbook pro is consistent in its temperatures.

    Maybe the heatsink isn't properly put on the NB on my imac. This would explain the higher NB temps with the rest of the system being quite normal. Of course, to bring it into service; I'll be laughed at... (even the power supply is at 48C; the NB is cooking away at 60... this can NOT be normal...)
     
  4. Hellhammer Moderator

    Hellhammer

    Staff Member

    Joined:
    Dec 10, 2008
    Location:
    Finland
    #4
    I meant your PC, iMac can't be overclocked

    Remember that CPU has its own cooler while NB doesn't
     
  5. fhall1 macrumors 68040

    fhall1

    Joined:
    Dec 18, 2007
    Location:
    (Central) NY State of mind
    #5
    Hopefully the NB is designed to run hot.....mine is consistently around 68 - 70C while my CPU is around 42C
     

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