Fan beeps

My computer boots up ok but after minutes, or even hours sometimes, of
running, the box starts to beep and a light flashes red/green on the front
of the case. The light that flashes is labeled 'fan fan'. Does anyone here
have a clue as to what it is that I need to look at. There has got to be 6
or so fans in this computer. I have removed and cleaned all of them. When
this problem first started, there was a forest of dust buildup inside
especially around the cpu fans.

jnwayn wrote:
> My computer boots up ok but after minutes, or even hours sometimes, of
> running, the box starts to beep and a light flashes red/green on the front
> of the case. The light that flashes is labeled 'fan fan'. Does anyone here
> have a clue as to what it is that I need to look at. There has got to be 6
> or so fans in this computer. I have removed and cleaned all of them. When
> this problem first started, there was a forest of dust buildup inside
> especially around the cpu fans.
>

Maybe the label reads "fan fail" ?

Is this a prebuilt computer ? What make and model ?

If it was home built, then maybe this fan thing is a separate
subsystem or something. You'd have to shed some light on what
is inside the box, to get more help. (Means taking the side
off, and figuring out what is stuffed in the box.) Observing
what the fans are wired to, is going to help you understand
what is monitoring the fans.

Motherboards sometimes use a SuperI/O chip that has a hardware
monitor section, to keep track of fans. There can be three to
five channels of fan monitoring. Each channel accepts as input,
an RPM signal from the fan. The signal pulses twice per
revolution. The signal is only available on three or four
wire fans. Many case fans have only two wires, so no monitoring
of those is normally possible. (The two wires carry +12V and GND,
and two wires is just enough to power the fan and make it spin.
RPM would be a third wire. PWM, or speed control, can be a
fourth wire. Cheap fans have only the two wires.)

Some server motherboards, can have more than one chip, and hence
additional monitoring features.

Once the ability to monitor RPMs is present, then it is up to
some BIOS or software feature, to decide how slow is too slow.

A more obscure feature, is a fan that has a locked rotor signal.
Such a feature may make it marginally easier to report fan
problems, as then no software is involved (that might make it
easier to drive a fan fail light). But LR fans aren't typically
used on computers.

Paul

"jnwayn" <jnwayn@bellsouth.net> wrote:
>My computer boots up ok but after minutes, or even hours sometimes, of
>running, the box starts to beep and a light flashes red/green on the front
>of the case. The light that flashes is labeled 'fan fan'. Does anyone here
>have a clue as to what it is that I need to look at. There has got to be 6
>or so fans in this computer. I have removed and cleaned all of them. When
>this problem first started, there was a forest of dust buildup inside
>especially around the cpu fans.

It could be a fan that is running too slowly. But I
would expect that to happen within minutes of startup
every time. If it is a fan, it should also get worse
relatively soon. (Also, did you oil the fans when you
cleaned them? The bushings on fans tend to dry up and
burn out. If you catch it soon enough, a single drop of
oil might keep it going for years.)

But given that it sometimes runs for hours first, I'd
expect it is a temperature sensor rather than a fan
sensor.

It doesn't make a lot of difference though, because it
all amounts to pretty much the same action being
required on your part.

Two avenues to approach this. One is just go blind,
like you did before, and try to spot a hardware problem.
Take the screws holding the case cover on out, but leave
the cover in place, and wait until it does it again.
Then pop the cover off and quickly inspect each fan.
Ideally, do this with fluorescent lighting, and you'll
be able to see a slower moving fan blade very easily.

You can also take the cpu fans and the heat sink out and
clean them up again. If it's a temperature sensor it is
likely that a cpu is overheating. You'll want to have
some thermal compound available to use when you put it
back together.

Another approach is to either get software that will
give you data from the fan and temp sensors or you might
be able to reboot and go to the setup menu and look at
the temps and fan readouts that are probably provided
there (rebooting may allow it to cool though, and you'll
never see it). Whatever, this might be the best way as
you will actually discover precisely what the cause is.

Some sensor monitoring software allows you to set the
values used for alarm points, and it is possible that
you've somehow managed to get one of them set too low,
and don't actually even have a problem at all!

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com

Have I missed something? Could you give me the exact configuration you
are using?

Board:
Board revision:
Bios:
Operating system:
Memory (Exact Type, Chip-Nr., how many DIMMs and where they are
inserted):
PCI card(s): (exact)
Hard Disks:
Raid Level or SATA:
CD-ROM drive:
Power Supply:

Rodger