Again, you have 3 options here for the fans (as with the temp sensors). You could have:
1. a "fan" entry in the firmware's output, but not wired anywhere in the board.
2. a "fan" entry physically connected to a fan output, but not connected to any fan.
3. a "fan" entry physically connected to a fan.

(I think in my board case there are no entries in 1.)
Each fan output can be individually controlled (with some logic programmed in the board's controller) selecting a desired voltage output (from 0 to 12V, represented by "percentage" in this plugin). This is achieved in hardware with a (pretty big) VRM chip (voltage regulator) for each fan that apparently heats up a lot (about ambient_temp+20C in my case, even for those VRM that are not powering any fan), to the point that those 4 VRMs optionally have a heat sink (that optionally can be connected to the water cooling system this board is intended to control). So yes, every fan controlled physically has a VRM temperature. I think is not relevant to monitor the temperature, speed and output for the fans not connected... although I'll make some tests to see what is the firmware reporting in that case and come up with a better logic here. One could have a fan without the 3rd cable to monitor the fanspeed, but still is interesting to know the output voltage the controller is providing, the current the fan is draining and the VRM temperature.