Thanks - it helped. My fans are Antec SmartCool fans with the Molex and
small extra plug. Look slike I have them connected right and now I just
have to find a way to control the fan speed from Linux.
I wish there was a way to have them idle until needed but I don't see any
way to do that except to look into some user-land utility so now I know
they're connected correctly I can look into what to do next.
There are many ways to control fans, and as with all things retail,
it is not that easy to kludge together something to give you a
degree of control.
Your SmartCool fan is designed such that you cannot easily control
it from software. If it uses a three wire cable with three pin
connector, there are more options for controlling a fan with a
regular three pin connector (I call that a "dumb" fan). Here is
an example of a device I use to crank down fixed speed fans,
to a more silent level. This doesn't give you a different speed
as the temperature changes. A dumb fan plus one of these is what
I like.
http://www.silentpcreview.com/files/images/fan_controller/fanmate1-2.jpg
I have an Antec power supply that has some "fan only" molex disk
drive connectors. The voltage on the "fan only" cable is determined
by the temp inside the power supply, so the fans running off those
cables will speed up if the case air gets hotter. Slapping
an Antec SmartCool onto one of those "fan only" connectors
would give you a fan that was so slow as to be useless. A
dumb fan connected to one of those would still be spinning.
If you wish a "zero cost" solution, you can take the SmartCool
fan, and rewire the connector, to connect the +12 and GND of the
fan, to the +12 and +5V pins on the Molex end. Since there are only
two pins installed in the Antec connector, you would be moving
one of the pins into a different hole. If you were to do this,
you can no longer hook up the tachometer signal to the motherboard
(the ground reference on the fan is now lifted to +5V, which is
no good for making the RPM signal work properly). While
this will work, I don't use this technique on my gear.
Original Position Modded Position (puts 7V across fan)
(By moving black wire and pin to the
+5V position on the connector.)
x x GND +12 +5 x x +12
Black Red Black Red
I have also used silicon diodes as voltage dropping devices.
A silicon diode drops roughly 0.7V when a decent current
flows through it, and by placing from one to seven diodes
in a row, you can drop 0.7V to 4.9V of applied voltage.
To do this, you cut the red +12V wire between the fan and
Molex, and install the diodes. The "band" around one end
of the diode (cathode) goes away from the Molex end. The
more diodes, the slower the fan goes, and the tachometer
signal on the separate three pin, is still valid when
doing this. (Because GND is still GND.) Diodes of type
1N4001 through 1N4007 can be used for a job like this,
and my local electronics store sells them in bags of 25
devices for a few dollars. (Some suppliers charge much
higher prices, making this too expensive as a solution.
I would not buy the diodes at Radio Shack, for example.)
band band
Molex | |
v v
x x GND +12 ------- diode --- diode ------------- the
| fan
+-------- original_black_GND_wire_untouched--- end
http://www.diodes.com/tracker/pdftr...om/products/catalog/search.php&ds=ds28002.pdf
For the ultimate control, some dumb fans plus a
T-Balancer gives programmable control.
http://www.tomshardware.com/2004/11/22/mcubed/index.html
http://www.mcubed-tech.com/eng/produkte.htm
HTH,
Paul