Question Can't control chassis fan speed


Junior Member
Jun 28, 2018
I recently started my 3rd PC build and have never ran into this issue before. I have Rosewill Prism S-Black case and a ASRock AB350 PRO4 motherboard. For some reason I cannot control any of the 4 pre-installed case fans neither through software nor through the BIOS. I have tried using the BIOS and set it to "silent mode" but that did not change the RPM of the fans. I dont know how to attach an image, but I would attach an image of what I think is the pre-installed fan controller if I could. It is on the back of the case and has all of the pre-installed fans connected to it. I have connected the controller to the power supply. I have not connected the VDG plug because the motherboard does not have a connector for it. I'm not sure what the problem is and how to solve it. Is my motherboard not compatible? Do I need to connect the fan controller to the motherboard? Any suggestions?


Elite Member
Super Moderator
May 4, 2000
The fan controller needs to be connected to the motherboard (or control the RPM directly on the fan controller on some models).

Generally you connect all the fans to the controller, and then a connector goes from the fan controller to the motherboard so you can adjust the speed. However, this is assuming you are using PWM fans as some fan controllers do not allow the control of 3-pin fans (and spins them at the max speed at all times).
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Diamond Member
Dec 10, 2010
Do the fans have 3-4 wires on them? If they only have two, it means they cannot be internally controlled. You would need to adjust the voltage going to them, and this is typically with a reostat or the like that you manually adjust.

What case did you get? This would help us help you.