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[Bug 209837] Re: [Acer Aspire 5720z] ACPI fan control problem


This bug is still present on recent kernels on ubuntu vivid.

I had to update aspire 5720z bios to 1.45 to solve the problem

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  [Acer Aspire 5720z] ACPI fan control problem

Status in linux package in Ubuntu:

Bug description:
   Hello! I bought an Acer Aspire 5720z laptop a half year ago. First I
  had 7.10, since february Hardy beta. Unfortunately I have the same
  ACPI problem with both versions: When I turn on the computer, the fan
  goes with full speed. After Ubuntu starts to boot, the fan stops
  suddenly. Usually the cpu overheats after about 30min and the bios
  turns the pc off. After turning it immediately on, and booting ubuntu,
  The fan speed goes up to max, but stays on the maximum forever.

   I changed my bios, but the it haven't solve this problem. Then I
  started to analyze acpi and found an interesting thing: Acpi gets only
  statically cpu-temp message by the booting.  When I start the pc it
  shows usually 40 C, but if I see the 'sensors' application, I can see
  that the real temperature goes upper and upper 50-60-70-80.... C and
  then the turning off by bios. ACPI shows always 40, so as it seems to
  be low, it won't ever start the fan. After the immediate restarting
  ACPI shows 70 C and it runs the cpufan on fullspeed. when I look at
  the sensors data, I can see, that the real cputemp comes down to
  25-35C. I can  also see cpu speed-step working well, only this fan is
  the problem for me. I would be very happy  if anyone knew the answer
  for this problem, and naturally I can help you with more infos, if you
  need. Thanx!!

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