Gentle Typhoon wire designations

[Jacko75]

I have Gentle Typhoons (500) for other than computer cooling purposes. They are very, very quiet indeed. There are Molex - equipped wires for easy computer connections. For my purposes I would like to know the wire designations. Probably Red is +12 V and Black -12V; at least the GT is happily and quietly running with these guesses. But what is the third, Yellow wire for ?

[Oli]

As the fans are designed primarily for use in PCs the yellow wire carries a speed signal to report the actual rpm to a PC mainboard with 3-pin molex connector. The mainboards BIOS and additional diagnosis software are then able to read out the rotation speed and sometimes to adjust it by voltage regulation.

The rest is as you described, red is the positive wire for 12V, black as mentioned.

[Jacko75]

Thanks, Oli