Controlling 4pin fan with PWM 25Khz

Using Arduino Programming Questions
7

Dual 25kHz PWM using Timer1 ...

//Dual 25kHz PWM using Timer1 Mode 10

word pwmA = 160; // 50% duty (0-320 = 0-100% duty cycle)
word pwmB = 288; // 90% duty (0-320 = 0-100% duty cycle)

void setup() {
  pinMode(9, OUTPUT);  //pwmA
  pinMode(10, OUTPUT); //pwmB

  TCCR1A = 0;            //clear timer registers
  TCCR1B = 0;
  TCNT1 = 0;

  TCCR1B |= _BV(CS10);   //no prescaler
  ICR1 = 320;            //PWM mode counts up 320 then down 320 counts (25kHz)

  OCR1A = pwmA;          //0-320 = 0-100% duty cycle
  TCCR1A |= _BV(COM1A1); //output A clear rising/set falling

  OCR1B = pwmB;          //0-320 = 0-100% duty cycle
  TCCR1A |= _BV(COM1B1); //output B clear rising/set falling

  TCCR1B |= _BV(WGM13);  //PWM mode with ICR1 Mode 10
  TCCR1A |= _BV(WGM11);  //WGM13:WGM10 set 1010
}

void loop() {}