Fan connector

I'm trying to quieten down an old Compaq ap400. I've found a much
quieter fan to fit into it but the new one only has two wires from it
and the old noisy one has three. The connector on the motherboard has
four prongs with a gap, something like this: | | | |
The connector wires a
black (gap) red (gap) yellow
Now, can I just connect the black and red wires, or is the yellow wire
a sensor or something?
I was also considering wiring it up to a molex and reducing it to a 7v
instead of a 12v, making it even quieter. Any help would be
appreciated, thanks.

Andy

On 6 Mar 2006 09:14:24 -0800, "Andy Cooper"
wrote:

I'm trying to quieten down an old Compaq ap400. I've found a much
quieter fan to fit into it but the new one only has two wires from it
and the old noisy one has three. The connector on the motherboard has
four prongs with a gap, something like this: | | | |
The connector wires a
black (gap) red (gap) yellow
Now, can I just connect the black and red wires, or is the yellow wire
a sensor or something?

The typical motherboard pins for a 3 pin header supply
(looking at it in same orientation as you are the fan plug &
wires):

Ground | 12V Pwr | RPM

On 4 pin headers (presumably following Intel's standard),
there's a PWM control on the last pin.
The yellow wire IS a sensor, but you can just connect the
black and red wires. The safest course of action would be
to take a multimeter and measure the voltage and continuity
to ground but without those all I can do is tell you the
standard header and that you could also check Compaq's
website if you want more confirmation. In general the fan
you already had could already be considered good evidence
and it's reasonable to just plug in the new fan and see if
the issue mentioned below is present- that the system alerts
that there is no RPM signal.


I was also considering wiring it up to a molex and reducing it to a 7v
instead of a 12v, making it even quieter. Any help would be
appreciated, thanks.

Yes you could do that instead. It is fairly
self-explanitory, wiring the positive to 12V and negative to
5V. The remaining issue then is whether the motherboard,
when it detects no RPM signal from the fan, displays an
annoying alert and/or requires you press a key to continue,
or if it is set to power off the system in such a (lack of
RPM) event. If this situation is present when trying it,
see if the bios allows disabling this feature (I've no idea
how Compaq might've worded the setting).

Thanks kony. The error bleep/notice was one of the things I was
concerned about, I think it's a 'critical something or other warning',
but i'll have to address that if and when it happens. Thankds again.

Andy

Hmm. I tried it and get the critical error and even though the fan is
running (on two wires), the bios says the fan has failed. anyone know a
workaround please?

thanks , Andy

On 8 Mar 2006 01:08:49 -0800, "Andy Cooper"
wrote:

Hmm. I tried it and get the critical error and even though the fan is
running (on two wires), the bios says the fan has failed. anyone know a
workaround please?

thanks , Andy


Only two options- either the bios allows disabling this (or
a more comprehensive error message(s), or you'd have to get
a fan with the RPM (sometimes called "tach") output.

Well there is another option, if you have another fan in the
system with RPM output, you could just plug that other fan
into this fan header and power the current fan from an
alternate.

kony wrote:
On 8 Mar 2006 01:08:49 -0800, "Andy Cooper"
wrote:

Hmm. I tried it and get the critical error and even though the fan is
running (on two wires), the bios says the fan has failed. anyone know a
workaround please?

thanks , Andy


Only two options- either the bios allows disabling this (or
a more comprehensive error message(s), or you'd have to get
a fan with the RPM (sometimes called "tach") output.

Well there is another option, if you have another fan in the
system with RPM output, you could just plug that other fan
into this fan header and power the current fan from an
alternate.

Ok , that gives me some ideas, thanks a lot kony )