Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
Thx for the info Paul.
Maybe next time i also should read the manual (RTFM).
Just need to treak the Temp to let Q-Fan to be enabled, had it set to high,
look like i have it ok now.
My Mobo always stay at 95F, the only fans i have in it, are the intel stock
fan, a 120mm chassis fan, that came with the case, and a coolermaster 80mm
fan near the HDDs.
The case i have is this
http://www.cluboverclocker.com/reviews/cases/foxconn/diabolic/
One of the best i have ever owned.
Leigh-Anne
"Paul" <nospam@needed.com> wrote in message
news:QVsed.35615$J16.2162510@news20.bellglobal.com...
> Leigh-Anne Mills wrote:
> > I have a P5AD2 Premium with a intel 3.6GHz on it, the procressor fans
runs
> > always 2567rpm and when the processor is at 100Percent the temp is 158F,
> > should the fan run at a higher speed, when the processor runs hotter, if
so
> > what am i doing wrong.
> >
> > Thx
> >
> > Leigh-Anne
> >
> 158F is 70C, and that is a magic temp for the processor. Your processor
> is thermal throttling - in other words, it is not running at full speed,
> and won't give a good benchmark in its current condition. The
> temperature would have risen even higher, if the processor hadn't
> reduced the percentage of cycles doing actual computing. (If throttling
> is not enough to keep it cool, eventually the processor will turn off
> the computer, so there is another level of control it hasn't used yet.)
>
> Looking at the manual, you have one complicated piece of machinery.
> The CPU fan header has four pins. Three of the pins are like any
> old fan header - they consist of +12V, GND, tachometer. In the
> good old days, you would vary the voltage on the +12V pin, to change
> the fan speed. This could be done with a linear control (i.e. a
> rheostat, fanbus, or similar names), or via PWM (pulse width
> modulation). PWM is a square wave signal, where the width of the
> pulse is varied. When a pulse is integrated (smoothed with a capacitor),
> a voltage results, and as the pulse width varies, the fan speed would
> vary because the filtered voltage is varying. In other words, a PWM
> method sources +12V to the fan, and can vary the voltage to the fan.
>
> So, those were the old methods for controlling the +12V pin.
>
> Also, in the good old days, Intel had a thermistor inside the fan body.
> Intel controlled the fan speed based on the air temperature passing
> through the fan body. The idea here is, the fan provides "constant
> cooling effort". If the air temperature rises, the fan has to move
> more air, to maintain the same die temperature. I've never seen those
> terms in print, so that is my best guess as to their misguided thinking.
> In this case, fan speed is minimal at 30C, and maxed at 38C or higher
> air temperature.
>
> Now, back to the present day. Your new CPU and its headsink/fan, have a
> fourth pin on the fan. It, too, is a PWM pin. The PWM feature works the
> same way as it would have on an old fan. The motherboard can send a
> square wave to the fan, and inside the fan, the square wave is used to
> vary the fan voltage. It is just the smoothing and switching that is
> being done inside the fan now, as the switching component can be kept
> cool as it lives inside the fan.
>
> The BIOS gets in on the fun at this point. The BIOS has three options.
>
> If you select "Q-fan Disabled", then the PWM signal is turned off, the
> fan gets full +12V power. The Intel fan, when not receiving a PWM
> signal, falls back to using the thermistor. If the air temp is 30C
> or less, the fan speed runs at min. If over 38C, the fan runs at max.
> That is probably what is happening to you right now - Q-fan is off
> and air temp is too low to make the fan run at full speed. Your
> computer case must be very well ventilated.
>
> When Q-fan is enabled, the BIOS has options for "DC" or "PWM"
> control. The DC option, means the motherboard does something to vary
> the +12V signal to the fan. The PWM signal, at this point, would be
> turned off. At the fan end, the fan thinks it is dealing
> with a "dumb" motherboard, so the fan is using its thermistor to control
> the fan speed. The fan runs slow, if the air temp is below 30C. The fan
> runs at full speed, if the air temp reaches 38C. The motherboard
> measures the CPU die temperature, and if the die is over 50C, the fan
> voltage will be ramped up. In this case, you are really at the mercy of
> the air temperature again, as at 70C die temperature, the fan receives
> the full +12V from the motherboard, but the thermistor still controls
> fan speed as well. (Or stated another way, there are two temperature
> control methods at work at the same time, and the Intel method
> dominates the other method.)
>
> If you select the "PWM" option in the BIOS, when Q-fan is enabled, then
> the 12V signal gets the full 12V, and the PWM signal is turned on. As
> in the "DC" control case, the motherboard measures the die temperature,
> and the fan speed is controlled via the PWM signal. The difference in
> this case, is the Intel fan stops using its thermistor, so if the
> die hits 50C, the fan should ramp up, and be running faster than it
> currently is.
>
> Based on reading the manual, and the datasheet for an LGA775 retail
> processor, I would say "enable Q-Fan, select PWM control" to fix
> your problem.
>
> I wish this had occurred to me before, because other people have
> complained about high processor temperatures, and it never
> occurred to me that the Asus defaults would be so stupid. I
> suspect a non-default setting is best.
>
> HTH,
> Paul
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