MoBo fan voltage

[yh125d]

Does anyone know the voltage sent to a fan when connected to a 3pin motherboard connection? I have some fans that have 3 and 4 pin connectors that I would like to plug into the mobo so I can monitor their speed, but do they get more voltage out of a 4 pin connector?

 

[Aluvus]

12 V, can be less if the motherboard supports dynamically reducing the voltage sent to fans. The 4-pin connectors use PWM (instead of simply reducing the voltage outright).