Three pin connectors are simply positive, negative, and RPM. Cut the wires, and connect the red and black to the red and black in the molex. My method is just splicing the end, folding the wires over and sticking them in the holes in the molex plug Then you could just use a bit of electrical tape and hold it all together.
(yeah yeah, it's too white...and no comments on the dust, this wasn't my PC )
Ok dont worry anymore guys. I looked at the other one's post and did some tweaking, and got it to work.
For anyone interested -
I took my fan and cut the red and black wire from the 4 pin molex connector, i then stripped the ends of to reveal bare wire.
I then got an old 3 pin connector plastic body.
Inserted the black and red wire and then hooked it up to my colle rmaster fan contoller - turned on my PC and nothing happened.
I jiggled the wires about and the fan started to power up.
Holding the wires in this position i turned the fan up to full speed and it worked - success!
So all i need to do now is tape the wires in the right place and im done - thanks for your help