You could control then via the BIOS.
Enter the BIOS and go into Advanced Mode (F7)
Select the Monitor tab.
Go into the Q-fan configuration.
You could select a fan profile (standard, silent, turbo and manual)
Manual will allow you to create your own fan sppeds.
Without doubt, you can solve this without using the Manual Profile option to set a custom fan curve - in fact, doing that alone would not solve your issue.
Your issue is a different fan header configuration option called the MODE. Unfortunately, your mobo manual does not even talk about that or show you where, but I'm sure it is there. See your manual, p. 2-1 and on. To get into BIOS Setup, reboot your machine and immediately hold down the "Del" key. Don't just tap it - hold it down until the opening screen of BIOS Setup appears. On the EZ Mode screen at bottom centre click on the QFan Control box. From here on your mobo has no info or pics. You will find that there are places to choose WHICH fan header on your mobo you are configuring, and they all are done separately. Your mobo has four CHA_FAN headers, and you should identify which have your fans on them. Choose one of them. You will have places to pick the fan Profile (like Standard, Quiet, Turbo, Manual) - set that to Standard or Normal. There will be a place to set the MODE, with choices like PWM and DC or Voltage. For your 3-pin fans, use the DC or Voltage setting, NOT the PWM. Now go on the the next CHA_FAN header and make the same settings. Continue for all the CHA_FAN headers. Do NOT do this for the CPU_FAN header unless you are having trouble with it. It probably has a 4-pin fan on it that does use the PWM Mode. When you are done, use Esc to get to Main Menu, then F10 to get to Exit Menu (p. 2-4). There choose Save Changes and Exit to save your new settings and reboot. Your fans should now be under automatic control based on a temperature sensor on the mobo, and they will run slower until you get your system hot with heavy work.