Question b450m ac unable to control chassis fan 2

a.choheyli

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Mar 30, 2018
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Hi. I have a b450m ac and I bought two "be quiet! Pure Wings 2 120mm PWM high-Speed". Now this motherboard has 4 pin for cha1 and a 3pin for cha2. These fans are both 4 pin.
In bios I can control fan for cha1 but I can't do it for the other one. It doesn't even show up. However it does show its speed which is over 2000 rpm and is a bit noisy.
I like these fans is there anyway to fix this? If I buy splitters would that solve the issue?
please give me suggestions as I'm very noob when it comes to these stuff.
 

Vyrvelata

Commendable
According to Asrock website only one of the fans is motherboard controlled....
You can use rpm reduction cable ....but they are expensive... maybe its better to buy lower rpm fan...


This is 6.99$

  • Reduce fan speed to help lower noise
  • Maintain PWM control function
  • Beautiful all black sleeved cable
  • Includes high capacity 3W 50Ω resistor
 
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a.choheyli

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Mar 30, 2018
30
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4,530
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According to Asrock website only one of the fans is motherboard controlled....
You can use rpm reduction cable ....but they are expensive... maybe its better to buy lower rpm fan...


This is 6.99$

  • Reduce fan speed to help lower noise
  • Maintain PWM control function
  • Beautiful all black sleeved cable
  • Includes high capacity 3W 50Ω resistor
Thanks for the reply. I was wondering what if I buy this https://www.ebay.com/itm/112377958498
and connect both fan to my cha1 which is working just fine at this moment.
 

Paperdoc

Champion
Ambassador
Yes, the solution to your problem is that Splitter. FYI here's the limiting factor. The CHA_FAN1 header can supply up to 1.0 A current to the connected load. Unfortunately beQuiet does not show us the max current draw for the fans you have, but virtually all such fans operate on less than 0.20 A per fan max, so you have NO problem connecting two of them to that header.

A mobo fan header can deal with the speed signal sent back to it form only ONE fan, so any Splitter will NOT send back more than one fan's signal. On that Splitter, the output with ALL FOUR of its pins can send its fan's signal back; the speed of the other fan cannot be reported. However, since they are identical fans, the speeds of the two will match pretty closely. This does NOT affect ability to control the fan speeds. It does, however, affect a secondary function. The header monitors its fan's speed signal for FAILURE and can warn you if this happens, When you use a Splitter and the speed of the second fan is not sent back, that fan cannot be monitored for failure. So from time to time YOU should just verify that both fans are working.
 
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a.choheyli

Reputable
Mar 30, 2018
30
0
4,530
0
Yes, the solution to your problem is that Splitter. FYI here's the limiting factor. The CHA_FAN1 header can supply up to 1.0 A current to the connected load. Unfortunately beQuiet does not show us the max current draw for the fans you have, but virtually all such fans operate on less than 0.20 A per fan max, so you have NO problem connecting two of them to that header.

A mobo fan header can deal with the speed signal sent back to it form only ONE fan, so any Splitter will NOT send back more than one fan's signal. On that Splitter, the output with ALL FOUR of its pins can send its fan's signal back; the speed of the other fan cannot be reported. However, since they are identical fans, the speeds of the two will match pretty closely. This does NOT affect ability to control the fan speeds. It does, however, affect a secondary function. The header monitors its fan's speed signal for FAILURE and can warn you if this happens, When you use a Splitter and the speed of the second fan is not sent back, that fan cannot be monitored for failure. So from time to time YOU should just verify that both fans are working.
Thanks for the info. I bare that in mind.
 

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