ASRock Extreme4 Z87 - fan not spinning at 20% but will at 30%?

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somegeek

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Nov 16, 2004

• Apr 18, 2014

• #1

Fan Header 101 question...

I'm setting up my fan profiles and I'm curious how the header works with the fan. When I set the header speed at 20%, the fan does nothing. When I move the slider up to 30% in A-tuner for the fan header, the fan starts spinning. Is there a minimum voltage or minimum RPM signal at which the fan will start to operate where it's too low when the header is set to 20%?

Appreciate any input.

somegeek

 

EarthDog

Gulper Nozzle Co-Owner

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• Apr 18, 2014

• #2

That is exactly it. Needs a certain.amount of voltage to even start.

 

OP

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somegeek

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Nov 16, 2004

• Apr 18, 2014

• Thread Starter
• #3

Thanks for the reply. OCD question... does the fan heat up at all if there's not enough juice to fire up the fan to move?

 

Last edited: Apr 18, 2014

RnRollie

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• Apr 22, 2014

• #4

Ohm's law or Ampere's law.. take your pick

 

ATMINSIDE

Sim Racing Aficionado Co-Owner

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Jun 28, 2012

• Apr 22, 2014

• #5

Yes, if the fan is at stall and receiving power it can be a fire hazard.

 

OP

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somegeek

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Nov 16, 2004

• Apr 22, 2014

• Thread Starter
• #6

I adjusted the minimum speeds accordingly and they all spin up nicely to a min RPM when the box is on now. 35-38% speed seemed to be the minimum to spin them up. Thanks for the replies.

 

OP

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somegeek

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Nov 16, 2004

• Apr 22, 2014

• Thread Starter
• #7

After further inspection, I'm learning the difference between PWM control and voltage control.

I have four identical model PWM (4-pin) case fans installed.

In the BIOS, a PWM header set at 5% speed for minimum temp = 650RPM for one of these fans. Same model fan on a voltage regulated header requires 43% speed setting to run at 650RPM at the minimum temp. After this realization, I was able to dial in my case fans more accurately to run quietly at idle and ramp up as needed.

 

RnRollie

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• Apr 23, 2014

• #8

If they are PWM, you can "daisy-chain" them with a good PWM splitter/cable, which makes life a LOT easier
However, do NOT use voltage control on PWM fans... they don't like it very much and something is going to break eventually.