What is the purpose of Q Control Fan?

[Denis54]

I have a P4P800 Deluxe. I know that Q control fan lowers fan speed but I would like to understand how it works.

Here are the readings I get with Motherboard Monitor 5:

Q Control Fan - Disabled: Fan = 25550 rpm, CPU = 43C, Case = 39C

Q Control Fan - Enabled at 11/16: Fan = 1750 rpm, CPU = 45C, Case = 41C

Edit: I should have written 2550 rpm instead of 25550

 

[shira]

This is a complete guess, but a pretty obvious one: It appears that when Q Control Fan is enabled, it increases or decreases the fan voltage based on the measured temperatures. The objective is to reduce case noise when the CPU doesn't need the full power of the fan. When Q Control Fan is disabled, the fan gets full voltage and runs at full speed. That simple.

Is there something more you were looking for?

 

[Denis54]

What puzzles me is that fan rpm is not constant when Q Control fan is Disabled. If I take the side cover from my case CPU fan speed decreases. If CPU load increases, then fan rpm increases.

If voltage was constant, I would feel rpm would also be constant. Is there something I do not understand?

 

[genghislegacy]

Just a wild guess as well, even if disabled, it might be still having some 'intellegence' to adjust to the environment?

Best is to shot an email to the tech support there.

 

[mrscintilla]

tried qfan on my a8n-sli. It slows down cpu, chasis1 fans' speed. But when I have a resistor on one of the fans, it will not read the speed correctly after the qfan was enabled. so basically, the qfan offers a slowdown in fan speed but may affect the reading of some fans' speed.