Question ASRock > Fatal1ty B150 Gaming K4 - Can't control my fan speed

Jun 10, 2020
my problem is that I buy one fan DCXFAN120 (3 pins) for my PC, btw I don't have problem with cooling my PC but I just wanna to add one fan for better airflow, I got Pure Rock - BK009 he is with 4 pins but this new fan DCXFAN120 is 3 pins and is running at 100% all the time I can't change the speed from BIOS I don't know why but if there is a solutions to make this new fan DCXFAN120 to run at lower RPM (to be more quiet) I'll be glad to hear.

Also I try with SpeedFan, it's showing me some speed on "Aux3 Fan" but when i try to go in "Configure" > "Speeds" ... and there is no "Aux3".



The reason your fan is running at 100% is because it's voltage regulated. The 4 pin is PWM which requires a signal to be sent to the fan in order to regulate the RPM. The signal wire being missing on your prior fan is why it's at 100%.

Now you can either get the same 4 pin connector fan like the Be Quiet! or you can try and find the option in BIOS to change the fan's RPM(for the connector the 3 pin fan is connected to).

On another note:
  • 1 x COM Port Header
  • 1 x TPM Header
  • 1 x Power LED and Speaker Header
  • 2 x CPU Fan Connectors (4-pin) (Smart Fan Speed Control)
  • 4 x Chassis Fan Connectors (4-pin) (Smart Fan Speed Control)*
  • 1 x 24 pin ATX Power Connector
  • 1 x 8 pin 12V Power Connector
  • 1 x PCIe Power Connector
  • 1 x Front Panel Audio Connector
  • 2 x USB 2.0 Headers (Support 4 USB 2.0 ports) (Supports ESD Protection (ASRock Full Spike Protection))
  • 1 x USB 3.1 Gen1 Header (Supports 2 USB 3.1 Gen1 ports) (Supports ESD Protection (ASRock Full Spike Protection))
*CPU_FAN1 and CHA_FAN1 can auto detect if 3-pin or 4-pin fan is in use.
The CPU Fan Connector supports the CPU fan of maximum 1A (12W) fan power.
Connect the 3 pin fan to the CHA_FAN1 header and see if that helps.
Reactions: stoqn.petrov
Jun 10, 2020
No chance to put it on CHA_FAN1 the cable is super short, that's why I use it on CHA_FAN3 :( And I try to find the option in BIOS to change the fan's RPM but nothing changes.