Power connectors

[ChemMan]

What's the purpose of having more than two wires on a power connector? In other words, why do connectors coming from your power supply (the ones used to power a case fan) have one red, one orange, and two black wires? Why do motherboard fan connectors have three wires? Thanks for answering my question.

 

[Zach]

The two blacks are just silly, two ground wires. THe yellow and red are 12 volts and 5 volts, I don't know which order. Fans have 12 volts and ground, and if there's a thord wire it's for RPM monitoring (a blip is sent for every time it spins around).

 

[Zach]

I just checked an old CDROM, and for trivia the yellow is 12v, the red 5v.