JD said:
Paul wrote:
JD wrote:
I have a CPU fan that runs all the time at around 4,100 rpm.
This is completely unnecessary when the weather is cool. I believe
a speed
of about 3,000 should be ok at present.
Is there any such program around? I know about SpeedFan but I think
it's a primitive piece of work. The CPU needs a delicate touch.
I did a search and found
http://wareseeker.com/free-cpu-fan-speed-control-software/
However it's hard to tell whether they are discussing the cpu speed
or the fan speed.
Anyone have experience of these?
TIA
Have you looked at your BIOS functions ? Maybe there is
an option in there to control the fan.
Paul
Great suggestion Paul.
I looked in the BIOS and found 2 options for the fan
Fan Control - [Enabled}
Lowest Fan Speed - [Slow]
The first one had no speed control as far as I could see and was the
existing
setting since the motherboard was installed
I set it to the 2nd one and rebooted.
It was exactly the same as before - whizzing along at 4,100 + or - a
few hundred.
I did have this fan plugged into the right socket - it is right
beside the CPU.
I looked in Control Panel - Add-remove hardware and it was no help.
Likewise in the Control Panel itself.
Do you know of any other possible location for a fan speed controller?
TIA
Maybe the next test, is to try Speedfan. If Speedfan cannot get any
response from the fan, then it could mean there simply isn't
a hardware feature there to control the speed with. (It could mean,
for example, that you've mixed incompatible components together.
Or that the motherboard makers are cheapskates.)
The rest of this is some background. Mixing a three pin fan with
a four pin fan header, may deprive you of a control method. And
that is an example of how you can accidentally be stuck with
a screaming fan.
*******
The CPU fan header has a couple features to control fan speed.
Back in the "three pin header" days, voltage control was used.
The fan normally runs from 12V. But the motherboard could control
the voltage, and deliver a variable voltage between 7V and 12V.
This would take a PWM output from the controller, and require a
MOSFET or transistor near the fan header, plus a capacitor,
to convert the pulse width modulated control signal, into
a voltage. It costs the motherboard maker some money to do that.
X <--- RPM (from fan to motherboard, for monitoring)
X ---> 7 to 12V to power fan
X --- Ground
If you're using Speedfan, Speedfan may find the registers that
control the PWM output. The register can be programmed, and
the hardware chip is then outputting a PWM signal. But if the
motherboard maker wants to save money, they don't bother to
install the interface circuit (the MOSFET and capacitor). Speedfan
cannot tell those components are missing. So one of the checks
I make, when someone has this problem, is to look at a picture
of the motherboard, and see if the appropriate looking components
are installed nearby.
(Some general rules of thumb. Prebuilt systems from HP/Dell/Gateway
are the ones most likely to have fan control per header. Which
means they have the most fan control of all. On an Asus motherboard,
the cheapest boards have no fan control. A board with QFan has the
CPU fan controlled. A higher end board with QFan2, has two headers
under control, one via CPU temp, one via chassis temp. So that should
give some idea what to expect in terms of working channels. With the
four pin fan header generation, you're much more likely to have a
CPU fan control, so the situation should be getting slightly better
as time passes.)
*******
The second control method, is of more recent design. Both
Intel and AMD now use four pin fan headers for CPU. The fourth pin
is (what a surprise) PWM. What is happening in this case,
is the responsibility for the MOSFET and capacitor, is now
up to the fan manufacturer, as they're inside the fan. The motherboard
has a fan controller interface on it somewhere (I can't say
right off hand, where this one is located now). The logic
signal output, running at perhaps 25KHz, is delivered on the
fourth wire of the fan. The fan runs at full 12V all the time.
The conversion circuit inside the fan hub, uses the pulse
width of the PWM signal, to control the voltage delivered
to the fan. That means the fan can run at 7V, using a
circuit inside the fan hub to make the 7V from the supplied
12V.
X ---> PWM (from motherboard to fan, 25KHz, indicates speed desired)
X <--- RPM (from fan to motherboard, for monitoring)
X ---> 12V DC (power from motherboard to fan)
X --- Ground
So as a consequence of having that fourth wire and control
method, Intel recommends not attempting to reduce the 12V
fed to such a fan. That recommendation, is so the MOSFET
has sufficient signal applied, so it will be biased properly.
Now, imagine what would happen, if you purchased an aftermarket
heatsink/fan combo, with a three pin connector, and connected
it to a four pin header. No PWM signal. No variable 12V.
And hence, no control method. Again, programs like Speedfan
will feel they're "dialing the knob", but nothing happens.
*******
There is one other feature, which was used in the past with
Intel fans. They had a thermistor in the fan hub. If the
computer case air temperature rises, the fan is set to
spin faster, based on the measurements by the thermistor.
That feature does not lend itself to control by the user.
Its purpose is to compensate for the worse cooling situation
caused by hot case air. So if the computer has poor ventilation,
the CPU fan may scream a lot more than it would in a cooler
running case. Any other control method applied, multiplies
its effect, by the effect provided by the thermistor. So if
the computer case was very cool, the fan may hardly be
turning at all.
Speed = Voltage_controlled_speed * thermistor_set_speed
Anyway, my next steps would be some Speedfan testing, and
some visual inspection. Like, checking whether there is a
three pin fan connected to a four pin header. On an older
motherboard, whether the appropriate components are next
to the three pin headers, and so on. As far as I know, there
isn't a programmatic way of determining whether the controls
are actually hooked up and working. A program could certainly
observe the RPMs, and notice that nothing is happening, but
I'm not aware of any program bothering to carry out such an
analysis for the user.
During the transition from three pin to four pin CPU fan
header, Asus made some motherboards with dual control
methods. The four pin header could be controlled as if
it was a three pin header. There was a BIOS setting,
that determined whether voltage control or PWM
control was used. And that means, on a small range of
motherboards, there is yet another BIOS setting to check
for. That practice was soon discontinued, in favor of
pure PWM control for four pin fan headers. Meaning
that the providers of aftermarket coolers, should
provide proper four pin fans, if they expected
satisfied customers. When you buy a retail CPU now,
from either Intel or AMD, you should expect to
find a four pin fan packaged with the retail CPU.
Paul
