Bill said:
Thank you very much.
One more question please.
The fans on the H105 are "PWM". Do you think it is normal for 1 fan of
the 2 radiator fans on the H-105 to run while the other sits and maybe
just "jiggles" a little (at low speeds). That is what drew my attention
to it in the first place, is that I could hear some very, very light
sounds (of the 2nd fan sort of trying).
They both run together at slightly higher speeds/heat. The two 3-pin
fans are co-joined by a simple wire "coupler" and are attached to the
4-pin CPU_OPT header. I can rationalize why it does what it does, and
I can rationalize why it shouldn't be doing what it's doing! Please
tell me the right answer, if you know!
Cheers,
Bill
By the way, gigabyte included some fan and temperature software with
their MB. Its doesn't work at advertised (where do the hours go?), but
it can be made to work.
That's not what is shown here.
I see two fans with separate four pin headers in this Newegg photo
for the H105. I can't find a picture of the pump, but it would make
sense for it to use a three pin.
http://images17.newegg.com/is/image/newegg/35-181-060-Z04?$S640$
(
http://www.newegg.com/Product/Product.aspx?Item=N82E16835181060 )
If a person wants to run fans in parallel, something must be
done about the RPM signal. The RPM signals cannot be joined
on the two fans. If I were to make an adapter cable, I'd either have
to disconnect RPM on one fan, or run the RPM signal of one fan, to an
"RPM only" connector to be run to some header that can measure
the RPMs for me.
FAN1 FAN2
+12V --------------X---------------X
GND --------------X---------------X
RPM --------------X
PWM --------------X---------------X
If I make an adapter cable like that, the 25KHz 5Vpp signal with
variable pulse width (PWM), controls both fans at the same time.
If the fans are a decent design, they should be within a 100 RPM
or so of one another. The match won't be perfect (due to maybe
friction differences or mechanical differences), but they should
be in the same performance ballpark.
In that diagram, only FAN1 has RPMs monitored, so you can see
the RPM rate in Speedfan.
I could make a two connector adapter, and route the RPM signal
of the second fan, to a three pin connector. Just for monitoring
and not for power. (My local electronics store (not RadioShack)
has a small, poor selection of connectors and pins so I can make
my own cables.)
FAN1 FAN2
+12V --------------X---------------X
GND --------------X---------------X (Yellow)
RPM --------------X X----------------+
PWM --------------X---------------X |
|
+12V |
GND |
RPM -----------------------------------------------+
Now, speed control is on the four pin, via PWM. Power is
drawn from that header too (so make sure the total fan
load in milliamps, does not exceed the milliamp rating
of the header. Both fans are commanded to do the same thing.
The second connector allows the RPMs to be measured.
You'll have to give me some idea what this "adapter"
is doing, for me to figure out what is going on. My
guess is, the second fan has radically wrong characteristics.
PWM fans are supposed to have something like a two
line response. When the control stays at 0 logic level
permanently (0% PWM), the fan should still be running
at a low speed. That's so your "low RPM" alarm doesn't
go off unnecessarily. You would need a more complicated
monitoring method (PWM, resulting RPM), to monitor
the fans otherwise.
RPM | /
| /
| /
| /
| -------
|
+--------------- PWM %
0 100
As to what the Corsair fans actually do, you'll need to
dig into some customer comments.
I wouldn't leave it hiccuping like that, if it was my rig.
I'd want to know "why".
*******
I found the quick install guide.
http://www.corsair.com/~/media/Corsair/download-files/manuals/cooling/H105_QSG_.pdf
On the one hand, the fan Y-cable, looks as expected. It
matches my first diagram, with RPM on the second fan
disconnected. That means, you cannot monitor RPM on
the second fan that way.
http://i58.tinypic.com/31788p3.gif
You would need to adjust the response curve, so the PWM
level doesn't drop so low, and allow the second fan to
get in trouble. In my PWM fan behavior curve, what is supposed
to happen, is the fan can't go below a regularly
spinning level. There shouldn't be a "fits and spurts"
level in the response. If the fan response curve was
a single line at 45 degree angle, extending to 0% PWM
input, then it's up to you, with your fan speed adjustment
software and method, to prevent the PWM signal from
dropping all the way to 0%. Maybe if the PWM signal
stays at 30% say, the fans will be in a regularly spinning
range.
If it was my rig:
1) Pumps runs at constant speed. The three pin header for it
likely doesn't have voltage adjustment in hardware anyway,
so this should be easy to meet. Verify, using Speedfan,
that the pump is in the right RPM range. If too high, there
could be air in the liquid loop. If too low, it could be that
the header isn't delivering +12V.
2) If I had the headers, I'd run the two fans separately.
But that would complicate fan control. It isn't that
common to have control software that couples two headers
in terms of settings and makes them do the same thing.
I expect that's why Corsair provided that Y cable. You
can use the Y cable if you want, but just make sure the
fan runs properly.
What would really be nice, is fan control software that
uses closed loop control. Where the RPM level was monitored,
the PWM value adjusted, for a "level of cooling". And that
"level of cooling" target was set by the temperature. That
would eliminate all the concerns. Only if the software
"hit the rails", and could not apply enough PWM to meet
the target, then it would alarm and put a dialog on the
screen saying something is wrong.
The same sort of thing happens with your car. There is
an acceptable control range, which varies as the car
ages. But if some control loop goes out of bounds,
maybe your car throws a code and "claims the oxygen
sensor is bad". So cars are an example of well applied
closed loop control, such that most of the time you
don't have to worry about engine management.
HTH,
Paul
)