| PhotoJohn...
i'm not sure with yours but alot of computer fans have extra wires to attatch to the motherborad of the computer to monitor the fan and tell it when to turn on and off etc... so this COULD be what that extra wire is... does it have a little tiny black connector? or is it connected to the bigger white connector like is shown in pic #4? also in Pic 4 you see a yellow wire that connects between the two connectors, but it gets cut off... | 
