CPU heatsink fan slowing down randomly

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

"Shantanu Sen" <sdsen@pacbell.net> wrote in message
news %s8d.6670$nj.759@newssvr13.news.prodigy.com...
> 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.
>

First, check the BIOS to see if any fan speed controls exist. Many new
motherboards can control fan speeds in relation to certain criteria that can
be adjusted by the end user. If there is fan speed control in the BIOS,
turn it OFF. It's possible that the motherboard is deliberately slowing
down the fan, and that the fan you have is particularly sensitive to voltage
fluctuation. If there is no fan speed control in the BIOS . . .

You need to replace that fan ASAP. If necessary, replace the whole HSF.

If the new fan does the same thing, then you have a voltage problem somehow.
Your power supply is a good one and so is your mainboard. You might want to
check to make sure that your mainboard is not shorting out to the case.
(are all your standoffs being used? Remove any that aren't) It's still
possible that your power supply or motherboard could be bad. IF so though,
I would suspect you'd have greater problems than a CPU fan slowing way down.
That's why I suggest you check ALL settings in the BIOS first. Start at the
PC health section. -Dave

Archived from groups: alt.comp.hardware.pc-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!

I don't think you've got a problem. I think your fan is being
slowed down to conserve power. As long as your CPU temperature
doesn't get to high, it doesn't matter how slow your fan is
turning, or if it is turning at all, for that matter. Go into the
software that triggers the alarm when the fan speed slows, and
lower it to 800 rpm. Then keep a close eye on your CPU temperature
for the next few days. If the CPU temperature goes up above 60 C
and the fan doesn't speed up, you *do* have a problem. But if the
fan speeds up when the temperature rises, and prevents the
temperature from getting too high, it is working as it is supposed
to work.

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

I did'nt see any message. As it turned out, that the alarm threshold for the
fan was set at 1200 rpm. After that I set it to 800 rpm and watched the
system over the
next few days. At low load when the temp hovers around 40 deg. celsius the
rpm is around 950-1000. When the load rises and the cpu temp moves up to
50+,
the prm automatically rises to 2000-3000 and brings the cpu temp down.

So, I was needlessly panicky...


"Matt" <matt@themattfella.zzzz.com> wrote in message
news:lakad.8958$k56.4287@news02.roc.ny...
> Shantanu Sen 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.
>
> Was there a message that went along with the alarm? Just what was the
> system alarmed about?

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

"Shantanu Sen" <sdsen@pacbell.net> wrote in message
news:yylad.27673$QJ3.233@newssvr21.news.prodigy.com...

>I did'nt see any message. As it turned out, that the alarm threshold for
>the
> fan was set at 1200 rpm. After that I set it to 800 rpm and watched the
> system over the
> next few days. At low load when the temp hovers around 40 deg. celsius the
> rpm is around 950-1000. When the load rises and the cpu temp moves up to
> 50+,
> the prm automatically rises to 2000-3000 and brings the cpu temp down.
>
> So, I was needlessly panicky...

No, you were being vigilant. A bad fan can cause the CPU to overheat in a
heartbeat and self-destruct. Your fan speeds of 950 sounds a bit low to me,
but not the temps, which are good. If you see temps above 60°C regularly
I'd consider an aftermarket HSF.