brushless 1/5 4wd conversion about to begin! couple questions.

[suicideneil]

Indeed, 99% of PC cooling fansd like this are BL- the white/yellow wire is the signal wire, so that when plugged into a fan controller or the PC's motherboard, the speed can be controlled to increase cooling when needed, or to decrease cooling & noise when not needed. The actual controller is built into the fan, you just vary the volts the vary the speed.