Case fans and their wiring.

Hello,
I want to add a toggle switch for a case fan I have at the top. It's a 12v fan which I think most all of the case fans are.

The other case fans have only a red and black wire. That must mean they are 5v fans right?

But this extra case fan I haven't put in yet, it's an LED one and it is 12V as its stated. But what baffles me is that it has 3 wires. One black, yellow, and one red. It states that the red is pos, black, neg, and yellow is F.G. Yellow. I don't know what that means. What is F.G. yellow? I assumed it would be the 12v positive because the molex's yellow wiring is 12v.

Funny thing is I have another fan I found, not LED and it also has three wire, but they are red, black, and white.

How do I wire these up?

THanks in advance!

Most case fans are 12V. Usually red wire is positive (12v) and black is negative (0v). The extra yellow/white/blue wire is a sensor for RPM.

Awesome, so I don't need to hook up the third wire. I can just tape it up and put it out of the way.

Thanks!