^ Yeah that.
Also, sometimes SF is a bit quirky with what it detects and when it detects them. My system basically stays the same, save for minor upgrades here and there. After a re-install, sometimes SF will only detect 75% of what it did the day before. After a few reboots, it sees the rest. Not sure why, just quirky sometimes.
Oh, and make sure you go into "Configure" and look under the Fan tab to make sure any relevant ones are checked.