CPU heatsink fan slowing down randomly

Archived from groups: alt.comp.hardware.homebuilt (More info?)

After setting up a new system, I ran it today for the first time for about
4 hrs. During the beginning (within the first 5 minutes) the heatsink fan
rpm dropped to around 930 and the digicell (the mboard monitor software
suuplied by the mboard manufacturer) started the alarm. I immediately
swtiched off the system. Then restarted it. It ran fine for the next ~4 hrs.
Then I heard the alarm again and saw the fan rpm again dropping to 930 from
~2940.

The CPU temp was between 37 and climbing to 41 (celsius) when the fan was
slowing down. Throughout the rest of the time, the CPU temp was between 37
and 41. I was not doing anything major with the system - the first time I
was just starting and the second time I was opening a large winzip file.

Any ideas why this might happen? I am now scared to leave the system running
and leave the room!

Can this be due to voltage fluctuations in the main board?

Here is my system info:

AMD Athlon 64 3200+ with the standard retail heatsink and Arctic Silver 5
thermal pad (since I had to re-seat the CPU once
and could not find the thermal paste recommended by AMD in any local store)
MSI K8N Neo FSR mainboard BIOS v1.4
Antec TruPower 380 W PSU and Antec Sonata case
Leadtek WinFast NVidia GeForce FX 5200 AGP Card
1 GB Patriot Ram
160GB SATA drive Western Digital
1 BTC 52241M CDROM drive
1 standard floppy drive
Windows XP

Thanks for any help,
Shantanu Sen
2 answers Last reply
More about heatsink slowing randomly
  1. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    On Tue, 05 Oct 2004 08:31:06 GMT, "Shantanu Sen"
    <sdsen@pacbell.net> wrote:

    > After setting up a new system, I ran it today for the first time for about
    >4 hrs. During the beginning (within the first 5 minutes) the heatsink fan
    >rpm dropped to around 930 and the digicell (the mboard monitor software
    >suuplied by the mboard manufacturer) started the alarm. I immediately
    >swtiched off the system. Then restarted it. It ran fine for the next ~4 hrs.
    >Then I heard the alarm again and saw the fan rpm again dropping to 930 from
    >~2940.
    >
    >The CPU temp was between 37 and climbing to 41 (celsius) when the fan was
    >slowing down. Throughout the rest of the time, the CPU temp was between 37
    >and 41. I was not doing anything major with the system - the first time I
    >was just starting and the second time I was opening a large winzip file.
    >
    >Any ideas why this might happen? I am now scared to leave the system running
    >and leave the room!
    >
    >Can this be due to voltage fluctuations in the main board?
    >
    >Here is my system info:
    >
    >AMD Athlon 64 3200+ with the standard retail heatsink and Arctic Silver 5
    >thermal pad (since I had to re-seat the CPU once
    >and could not find the thermal paste recommended by AMD in any local store)
    >MSI K8N Neo FSR mainboard BIOS v1.4
    >Antec TruPower 380 W PSU and Antec Sonata case
    >Leadtek WinFast NVidia GeForce FX 5200 AGP Card
    >1 GB Patriot Ram
    >160GB SATA drive Western Digital
    >1 BTC 52241M CDROM drive
    >1 standard floppy drive
    >Windows XP
    >
    >Thanks for any help,
    >Shantanu Sen

    I think that board has a fan control feature, that reduces
    fan RPM to reduce noise/wear/dust/etc, then raises it again
    if CPU were to get too hot. CPU is not too hot at 41C, but
    you then have a different problem, that the particular fan
    you use is dropping to an RPM lower than the software
    considers acceptible. That doesn't mean it IS an
    unacceptible fan RPM, only that it's unexpected by the
    software.

    So long as CPU temp stays at acceptible levels (below 60C
    generally) and the fan doesn't start wobbling or making a
    lot of noise (a sign that it's bearing is worn out, rather
    than an intentional RPM reduction by the motherboard) you
    can leave it alone, knowing it's going to be quieter than
    average and promote longer fan lifespan and service
    intervals... you are near the ideal with that setup, I
    wouldn't use a different fan myself.

    Those fan control circuits do not (generally, none that I'm
    aware of) actually control fan speed based on sensing the
    RPM, rather they just reduce and increase voltage or PWM
    power control linearly(?) based on CPU temp.

    You'll have to check the software to see if you can set a
    different minimum RPM value for the alarm. If you can't,
    then either don't use that software or use a different fan
    with higher default RPM. You might find other software
    (like Motherboard Monitor) will work but I've never tried it
    with that particular board.
  2. Archived from groups: alt.comp.hardware.homebuilt (More info?)

    I've seen some that you set the alarm in the bios.
    BruceM


    "kony" <spam@spam.com> wrote in message
    news:p1o4m0lm6vd4alrdinvptt5fejrln7gjit@4ax.com...
    > On Tue, 05 Oct 2004 08:31:06 GMT, "Shantanu Sen"
    > <sdsen@pacbell.net> wrote:
    >
    > > After setting up a new system, I ran it today for the first time for
    about
    > >4 hrs. During the beginning (within the first 5 minutes) the heatsink fan
    > >rpm dropped to around 930 and the digicell (the mboard monitor software
    > >suuplied by the mboard manufacturer) started the alarm. I immediately
    > >swtiched off the system. Then restarted it. It ran fine for the next ~4
    hrs.
    > >Then I heard the alarm again and saw the fan rpm again dropping to 930
    from
    > >~2940.
    > >
    > >The CPU temp was between 37 and climbing to 41 (celsius) when the fan was
    > >slowing down. Throughout the rest of the time, the CPU temp was between
    37
    > >and 41. I was not doing anything major with the system - the first time I
    > >was just starting and the second time I was opening a large winzip file.
    > >
    > >Any ideas why this might happen? I am now scared to leave the system
    running
    > >and leave the room!
    > >
    > >Can this be due to voltage fluctuations in the main board?
    > >
    > >Here is my system info:
    > >
    > >AMD Athlon 64 3200+ with the standard retail heatsink and Arctic Silver 5
    > >thermal pad (since I had to re-seat the CPU once
    > >and could not find the thermal paste recommended by AMD in any local
    store)
    > >MSI K8N Neo FSR mainboard BIOS v1.4
    > >Antec TruPower 380 W PSU and Antec Sonata case
    > >Leadtek WinFast NVidia GeForce FX 5200 AGP Card
    > >1 GB Patriot Ram
    > >160GB SATA drive Western Digital
    > >1 BTC 52241M CDROM drive
    > >1 standard floppy drive
    > >Windows XP
    > >
    > >Thanks for any help,
    > >Shantanu Sen
    >
    > I think that board has a fan control feature, that reduces
    > fan RPM to reduce noise/wear/dust/etc, then raises it again
    > if CPU were to get too hot. CPU is not too hot at 41C, but
    > you then have a different problem, that the particular fan
    > you use is dropping to an RPM lower than the software
    > considers acceptible. That doesn't mean it IS an
    > unacceptible fan RPM, only that it's unexpected by the
    > software.
    >
    > So long as CPU temp stays at acceptible levels (below 60C
    > generally) and the fan doesn't start wobbling or making a
    > lot of noise (a sign that it's bearing is worn out, rather
    > than an intentional RPM reduction by the motherboard) you
    > can leave it alone, knowing it's going to be quieter than
    > average and promote longer fan lifespan and service
    > intervals... you are near the ideal with that setup, I
    > wouldn't use a different fan myself.
    >
    > Those fan control circuits do not (generally, none that I'm
    > aware of) actually control fan speed based on sensing the
    > RPM, rather they just reduce and increase voltage or PWM
    > power control linearly(?) based on CPU temp.
    >
    > You'll have to check the software to see if you can set a
    > different minimum RPM value for the alarm. If you can't,
    > then either don't use that software or use a different fan
    > with higher default RPM. You might find other software
    > (like Motherboard Monitor) will work but I've never tried it
    > with that particular board.
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