The speed of S4028-15K can be adjusted using PWM signal from the motherboard. Please follow this procedure to adjust the settings on your motherboard.
To control more than 5 fans from one unique header, we recommend you to use the ARCTIC Case Fan
Hub. Its external SATA power will circumvent the header current limitation.
PWM Frequency: Target frequency 25 kHz, acceptable operational range 21 kHz to 28 kHz
Maximum voltage for logic low: VIL = 0.8 V
Absolute maximum current sourced: lmax = 5 mA (short circuit current)
Absolute maximum voltage level: VMax = 5.25 V (open circuit voltage)