Aux Fan Speed
The option description:
The given information option allows to specify current rotational speed of the additional fan of the system unit connected to an appropriate connector on the motherboard.
If the motherboard admits connection of several case fans, the options displaying speed of remaining fans nearby will be presented.
When the additional fan has no built in tachometer or is connected directly to the power unit, instead of real value is deduced  or [NA].
At some implementations BIOS there is a color selection of the deduced information. If number of turns within norm, you see dark blue digits if it fell to too low values, color of digits will be replaced with the red. However, the warning system quite often erraticly works at usage of the low-speed fan, even when it works in a regular mode. If notifying inscriptions at a loading stage are thus deduced, the sound signaling turnes on, control of speed of the fan is necessary for disconnecting, selecting for an option value [Disabled] or [Ignore]. In all remaining cases there is no necessity for the monitoring prohibition.
Other options identical to destination: