Jim said:
I'm buying some 3 pin fractal design fans in the next day or so, but
they will be married to a fan controller that only has molex connectors,
any ideas what cable i will need and given i have 5 fans will i need 5
cables, sorry for the noob question
http://www.quietpc.com/products/fractaldesignfans/fd-fan-120
http://www.quietpc.com/products/casefanaccessories/ae-f6xt
Jim
First, there is a manual here, for the F6XT.
http://www.aerocool.us/peripheral/f6xt/manual_f6xt.gif
It looks like the unit gets input power via a Y cable (so the
Molex can be daisy-chained if needed). The manual is not
specific, but my guess would be, a yellow and black wire
are present on each Molex 1x4, and a voltage up to 12V will
be placed on the yellow wire. (Proper Molex wiring uses a
fixed color code, and in this application, they don't have to
stick with the standard colors. Normally, +5V is red, GND is
black, and +12V is yellow.)
The F6XT controls are fixed at three speeds. "High" would likely
correspond to the full 12V. And the other two settings, would
be some slightly lower voltage.
You won't have any way to monitor RPMs of the fan blades that
way. If you use three pin fans, you'd need an adapter that
picks off the RPM signal, and forwards it to the motherboard,
and those are not easy to find (I only have one cable assembly
like that here, one I got years ago). I've stopped trying to buy
cables like that, and I just build my own cables. My local
electronics store (not Radio Shack), stocks TX3 connectors
and pins, so I can make fan cables when I need to.
This is an example of a Molex to fan adapter. This one is
daisy-chain capable, which you probably wouldn't want. Notice
that the RPM pin is not connected. The three pin connector, only
has two pins installed.
http://www.svc.com/3pinto4pinad.html
This is the same kind of thing, only without daisy-chain
capability on the Molex. But way too expensive.
http://www.amazon.com/3pin-power-4p...BK/ref=sr_1_11?ie=UTF8&qid=1335990470&sr=8-11
In this example, they call the small connector a "TX3". This
would be similar to the SVC one, only again, too expensive.
http://www.amazon.com/StarTech-com-...DQ/ref=sr_1_17?ie=UTF8&qid=1335990559&sr=8-17
And finally, this one is RPM capable.
http://www.amazon.com/Rosewill-powe...RC/ref=sr_1_19?ie=UTF8&qid=1335990623&sr=8-19
There are two TX3 connectors on the Rosewill. The male connector
with the three wires, goes to the three pin fan. The yellow wire is RPM and
it is brought back to a female TX3 with yellow and black. You'd
plug that female into a motherboard header that monitors RPM, if you
wanted to measure the fan speed for some reason. There are some
caveats with that though, in that for the RPM signal to work,
the fan needs the appropriate voltage and offset. If the
"thing" controlling the fan is a bit too clever of a design,
the fan voltage ends up "offset" above the motherboard voltages,
and then the RPM signal cannot be detected. The RPM signal works
most often, if the fan is powered from regular +12V and GND.
There are various tricks for wiring fans, like running between
the +12V and +5V power leads, that cause the RPM to not work.
The Rosewill is a decent compromise, in that it does make RPM
measurement possible, and if the F6XT screws around with the
voltages the wrong way, you can always leave the connector with
the yellow and black wire, disconnected from the motherboard.
It's not going to short to anything, because it's a female. And
the male connector on the Rosewill, has a shroud to cover the pins
a bit. There are some male TX3 connectors, that don't have a shroud,
and you need to cover them if they're not being used temporarily.
Or they're short to something inside the computer case (unless
the cable is unplugged entirely).
One thing about TX3 connectors with a shroud, is you can't plug
an "oversized" connector into the TX3, if it is protected.
On an unprotected TX3, you can plug a TX4 and shift it one
pin towards the left or right (as appropriate). So if you were
connected a PWM capable fan to the F6XT, then the shroud on the
Rosewill would get in the way.
I think you can see why I make my own cables, because this
rapidly becomes a rat hole. There are so many ifs/ands/buts
you can't keep up with it
I'd use the Rosewill one in your case, as it's the best balance
between functionality and price. The second link, the one with
just a single Molex and a three pin, that's closest to precisely
solving your requirement, but without any option in the future to
measure RPM with it. Measuring RPM isn't too important, but
some people like it. I couldn't tell you, the last time I
needed to check mine. I just listen for them...
Paul
