Please check the config to make sure you are not stuck with a fan simply not being able to fit.
To confirm you have
CPUFan, Sysafan1, Sysfan2, and Sysfan3 on the board all populated with fans.
You may also want to use other software to see if they detect fans as well.
Open Hardware Monitor - Very similar to Hwmonitor, but with some extra features. Open Hardware Monitor does not see my ups status while Hwmmonitor does. Open Hardware Monitor also allows fan speed, but it is manual only.http://openhardwaremonitor.org/
You can either slow the fans with software or your finger to see what fans are showing on what sensors in software.