yum install install i8kutils 
yum install lm_sensors.x86_64
echo "i8k" > /etc/modules-load.d/i8k.conf
# Now, one can manage fan speed.
i8kfan 1 1

I run this script into console (as watch command parameter) every 900s.

#!/bin/bash

SCRIPT_NAME=`basename $0`
FILE_TMP="/tmp/sensors-$SCRIPT_NAME"
sensors > $FILE_TMP

TEMP4=`grep temp4 $FILE_TMP | sed 's/\s//g'  | awk -F ":" '{print $2}' | sed 's/[^0-9.]//g'`
TEMP4=`printf %d "$TEMP4" 2>/dev/null`

FAN_SPEED=`grep fan2 $FILE_TMP | sed 's/\s//g' | awk -F ":" '{print $2}' | sed 's/[^0-9.]//g'`
FAN_SPEED=`printf %d "$FAN_SPEED" 2>/dev/null`

if [ "$TEMP4" -lt "72" ] && [ "$TEMP4" -gt "50" ] ; then
    if [ "$FAN_SPEED" -gt "100000" ]; then
        notify-send "Fan rotation has been just limited." "TEMP4=$TEMP4, fan2: $FAN_SPEED" -u low -t 2000
        /usr/bin/i8kfan 1 1
    fi
fi