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Does the Pentium M Processor indirectly control fan speed (laptop)

Discussion in 'Laptops' started by Sanjay Punjab, Jan 21, 2004.

  1. I own a fujitsu lifebook and the fan seems to have a life of its own.
    Turning on and off randomly and racing periodically. It is hard to
    explain, but the operating is erratic and my friend's identical laptop
    does not suffer from this problem. The laptop has a Pentium M
    processor. Fujitsu already replaced the motherboard (including CPU)
    and the fan & heatsink, but still the problem exists. I am wondering
    if the problem could be the hard drive, especially when the erratic
    operation seems to coincide with hard drive operations.
    The hard drive has that new S.M.A.R.T. interface that reports
    temperature. I am wondering if the Pentium M processor is giving a
    false signal to the fan controller chip based on faulty temperature
    data from the hard drive via the S.M.A.R.T. interface.
    I would appreciate any info on this. Thanks
     
    Sanjay Punjab, Jan 21, 2004
    #1
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  2. "Sanjay Punjab" wrote ...
    The processor (Pentium or whatever) only does what it is
    told by the people who wrote the BIOS code, and the BIOS
    does what it thinks is best based on the information it thinks
    it is getting from the temperature sensors, etc. Seems unlikely
    that they would run what is essentially the CPU fan based on
    heat information from the hard drive, but maybe it is designed
    to provide cooling to both?

    Is this really a serious problem? What do Fujitsu say? If they
    have already replaced the mobo/CPU I'd assume that you would
    either have to live with it or sell/trade it if it really bugs you.
     
    Richard Crowley, Jan 21, 2004
    #2
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  3. snip

    If your friend's is identical including the drive, peripherals and
    O/S then it must be application or usage related i.e location,
    ambient temperature, ventilation etc. ACPI power management used
    in all recent laptops can cause unpredicatble fan activity/results
    if the O/S is not that laptop model vendor supplied or supported
    -- read Windows (probably per some sticker too).
     
    H. Dziardziel, Jan 21, 2004
    #3
  4. (Sanjay Punjab) wrote in
    On my Acer TravelMate 800 (Pentium-M) I noticed that fan activity depends
    not on CPU temperature but on CPU activity/load. For example, using
    scanner on USB raises CPU load during scan, and that kicks fan on
    immediately. This is stupid design from manufacturer, but I learned to
    live with it.

    Alexei
     
    Alexei Boukirev, Jan 21, 2004
    #4
  5. Well, actually CPU temperature depends on CPU
    activity/load. Especially in a portable environment
    where pieces are slowed/shut down when not in use
    to preserve battery life.
    Not clear why this seems "stupid" to you? Would you
    rather that it run at full speed/power all the time? Suck
    the battery life for nothing? Run the fan all the time? Why?

    I see the same effect in my big tower machine at home
    that I use for editing video. As soon as I start rendering
    DV, I can hear the CPU fan speed increase. When it
    slows back down, I know it is done.
     
    Richard Crowley, Jan 21, 2004
    #5
  6. It does, but not directly. Short rare spikes of high activity do not raise
    temperature enough that turning fan on should be required. Yet, TM800
    turns on fan each and every time.
    See above.

    Alexei
     
    Alexei Boukirev, Jan 21, 2004
    #6
  7. Sanjay Punjab

    Robert Myers Guest

    Period. And it makes no sense to run the fan more than necessary. Do
    you and your friend use the laptop identically? Do you run the same
    programs, always having it resting on a hard surface so that vents are
    not randomly blocked, say, by sitting in your lap? How attentive is
    your friend to his computer? Does his "No, my computer never does
    that" really mean it happens in situations where there are enough
    distractions that he would never notice? Sit the two computers side
    by side and perform a controlled experiment, if his computer really
    *is* identical (same GHz, same memory, same disk)? No, you already
    said the disk drives are different, and yes, disk operation can affect
    the fan.

    Nice of Fujitsu to replace all that stuff. No big surprise that it
    didn't change anything. Find something else to worry about.

    RM



    Seems unlikely
     
    Robert Myers, Jan 21, 2004
    #7
  8. Sanjay Punjab

    Andre Guest

    I owned a Toshiba laptop, and a BKPW Note Pro like this, its a
    "feature" that keeps the processor at the same temperature while
    maximising battery life (reducing the fan speed during low CPU usage,
    and increasing it when the CPU is being thrashed, such as a lot of
    3D).

    You might try looking in the BIOS for anything like "Fan mode
    settings" or similar, sometimes they give you the option of turning
    off the demand based fan speed.

    -A
     
    Andre, Jan 21, 2004
    #8
  9. Howdy!

    So it should wait to turn it on? The fan control logic doesn't know
    how long your task will run - and it could easily be a design criteria to
    keep the temp down as low as possible concurrent with decent battery life.

    Doesn't sound so bad to me,honestly.

    RwP
     
    Ralph Wade Phillips, Jan 22, 2004
    #9
  10. It should turn on when temperature reaches certain level.
    To prove my point let's see a different situation - medium CPU load for a
    long time raises temperature significantly (much higher than after that
    short spike of load), yet fan does not turn on. Is that a good design?
    No way.

    The idea is to keep temperature down, so that should be a controlled
    parameter. You do not control engine temperature and cooling by
    measuring how fast the car goes, you do it with a thermal sensor.

    Alexei
     
    Alexei Boukirev, Jan 22, 2004
    #10
  11. It sounds like that is exactly what it is trying to do.
    That was the "state of the art" solution from 100 years ago.
    Computers (and even vehicles!) are much more sophisticated
    than that these days. They can anticipate need, and even "learn"
    usage patterns. The machines are getting smarter than us whether
    we like it or not! :)
     
    Richard Crowley, Jan 22, 2004
    #11
  12. This reminds me of Microsoft Word, which sometimes keeps capitalising some
    words whether I like it or not :) I get really frustrated when I'm forced
    to go back and change letter case to what it should be (what I originally
    entered). "Smartness" have both good and bad sides.

    Unfortunatly with some laptops, when you enter BIOS, you only have a choice
    to let it control fan in a "smart" way or have fan always on. What I want
    is a choice to control fan in "normal" way, i.e. depending on CPU
    temperature (well, maybe add ambient temperature influence there).

    Alexei
     
    Alexei Boukirev, Jan 22, 2004
    #12
  13. Mostly negative IMO. The newer versions of Windows
    seem to be HARD WIRED to paste WITH formatting and
    it is driving me completely up the wall. I am forced to go
    through a menu item just to get plain old-fashioned "dumb"
    paste. And sometimes the option isn't available at all! 8-{
     
    Richard Crowley, Jan 23, 2004
    #13
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