Question Can I control somehow the fan speed on startup on a poor chinese molex fan hub ?

alitiz

Prominent
Oct 17, 2020
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I bought some coolmoon fans half a year ago that came with a fan hub that connects directly to the psu. It also came with a controller so I can control the speed of the fans, the colors etc. but the problem is everytime i turn on the pc they run at full speed and i have to lower it using the controller every time.

I just need the fans to run at a lower speed when the pc starts, is that even possible ?
 
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Paperdoc

Polypheme
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Very likely not possible. That controller is very UNlikely to have any "permanent" memory like EEPROM that can store a setting while shut down. So it will always start up in a default mode (full speed) and require that you make your own changes.

You probably should not do that, anyway. If you apply a voltage to a fan that is too low (typically, below 7 Volts) it may never start up! But it WILL draw a current (and generate heat) while it is NOT running and hence NOT able to cool itself. You CAN give it a lower voltage once it IS running - often as low as 5 V), but if it stalls, it will NOT start up again until you raise that voltage significantly. For that reason, all mobo automatic fan headers normally start EVERY fan at the full 12 VDC power setting to ensure it DOES start at full speed. AFTER a few seconds it slows the fans down to the reduced voltage required for cooling at that time.
 
Jul 5, 2020
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I think the best thing is to adjust in Bios so it starts at a low speed and then use controller to turn up. I assume you don't like the initial blast/noise/power allotment? If you are manually turning down. Leave down in Bios and then turn up as needed. Can't you also set a profile in software so that it stays low at first. Otherwise there might be other hardware options. https://windowsreport.com/best-fan-speed-controller/
 

Paperdoc

Polypheme
Ambassador
We cannot know about this part because OP has not told us exactly what fan and hub system is involved. But POSSIBLE problems include:
  1. The fans may NOT have standard connectors on their cables, so it may not be possible to connect to mobo fan headers and ignore the hub.
  2. Likewise, without those standard connectors you could not plug them into a different third-party Controller.
  3. Similarly, the hub may NOT have any way to accept a fan control signal from a mobo header. You would need that feature to allow mobo control of fans that remain connected to the hub.
 
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