Fans??

Ok so i was going to add two intake fans on the front of my comp so i had 2 old power supplyies laying arount not even 150w. so i open them up and take out the fans. i got to my motherboard and see it needs a 3 pin connector and my fans only have two so i get the old voltage tester out but i end up sort curcuiting my cpu but everything still works so i want to know how i can fix this.

the fans are 12v (almost certain) i wouldnt plug them into the motherboard (this can have ill effects i have heard, and you dont want to mess with the motherboard anymore anyways ). i would plug them into a molex connector. one of the wires from the fan is for the 12v (yellow wire on molex connector)and one for the ground(black wire next to yellow wire), you just have to figure out which is which

if 1 wire is red and 1 is black coming fron the fan, then my best guess is red-yellow on the molex and black to black on the molex. good luck