# Explained: ASUS Q-fan function



## de.das.dude (Jan 22, 2011)

Well, this will be a lame thread i know. But my mobo manual didint quite explain the q-fan function properly. Internet failed me, so i tried tweaking and now have enough knowledge of this subject and thought i should share.



This Q-fan function is found on most new mobos from ASUS.
This basically controls the speed of the CPU fan at different temps. more like how it should behave.


the first option is to enable or disable it.
enabling this uncovers 3 more options,

the start voltage,
start temp and the temp at which fan speed should be max.


*The Start Voltage.*
this is the voltage which will be applied to the PWM wire of the fan till the required "start temp" is achieved by the CPU.
If you want quiet running(the main reason for enabling this function). you should set this at 4V, the lowest available.

*The Start Speed Temp*
This the temp from which there will be a linear increase in the CPU fan's RPM till the max RPM temp is hit. For quiet running, set this to the highest possible. i like to keep it at 40C though.


*The Max Speed temp.*
This is the temp where the fan will hit max RPM, and hopefully not, if the CPU temp still increases, the fan will maintain constant high speed.



For max cooling i encourage you to disable this function as the default mode seemed to do a better job for me(tested on my current setup, see specs)





thanks for the thanks


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## CBRworm (Jan 26, 2011)

Hmmm, my Q-fan options are different.


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## mastrdrver (Jan 26, 2011)

Yea Asus changed them to be more tweakable and useable when the P55 came out. On the AMD side I'm not sure when it was but seeing as de.das.dude is using a 785G board I would guess then as I don't think any of the other 700 series Asus AMD boards received anything but the older way of Q-Fan.


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## de.das.dude (Jan 26, 2011)

well my mobo is 4monhs old. so i guess they didnt change in all the places.


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## AsRock (Jan 26, 2011)

Q fan pisses me off it's some thing they should of perfected by now.  Like i can set the CPU fan to a nice silent speed and when it gets hotter it goes faster but once it's cooled down it stays at high speed.

I been hoping Zalman get their thumbs out of their butts and perfect the ZM-MFC2 already. Like for example when using 3 pin fans you could use the heat sensors to control the fan speeds.

So for each fan would have 2-3 different speeds depending on what the sensor picked up.


Maybe one day they will do it right  LMAO.


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## mastrdrver (Jan 26, 2011)

de.das.dude said:


> well my mobo is 4monhs old. so i guess they didnt change in all the places.



No yours is the new Q-Fan. The old one would tie all the 3 pin fan headers (except the psu one) to one setting and you got three choices: standard, turbo, and silent. The cpu had the same kind of settings but it was only for itself and as far as I know only works with 4 pin pwm fans.

edit: Went and looked up bios pics of your board and your right that it is still setup the old way.



AsRock said:


> Q fan pisses me off it's some thing they should of perfected by now.  Like i can set the CPU fan to a nice silent speed and when it gets hotter it goes faster but once it's cooled down it stays at high speed.



Sounds like a bios problem that should be easily fixed once it is.


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## CBRworm (Jan 26, 2011)

My current board has standard, silent, turbo and manual for CPU and Chassis.  when set to manual you can set low and high temps and PWM percents for those temps.  They limit chassis fan min to 60% which seems high, CPU you can drop to zero% but the fan still spins slowly below that set point - works pretty well but is not yet perfect.

The QFan software in windows will let you set points on a temp curve and assign PWM % to each point, but the software has to be running for it to work.


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## erixx (Jan 26, 2011)

My P55 Asus board has those options in BIOS, but many more in the AI-Suite. It works really well: anytime you do a game, benchmark or so, the CPU and chasis fans will start to speed up (and then down of course.)

Only bad point most Asus board are OR 3-pin OR 4-pin for the CPU, not both at the same time. 

An yes, De.DasDude, the documentation is POOR POOR POOR: no improvement in mobo Manuals since 20 years!!


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