What do it get it power from?

I'm not sure exactly what you're asking. Your computer has a power supply that feeds power to all the components.

Questions & Answers: Computer PC Cooling Radiator System 4 Channel 3 pin 4 pin Cooler Fan RPM Speed Controller w/ PCI Slot Rear Bracket for fan 12 v - power by molex 4pin

double click image to zoom in

Computer PC Cooling Radiator System 4 Channel 3 pin 4 pin Cooler Fan RPM Speed Controller w/ PCI Slot Rear Bracket for fan 12 v - power by molex 4pin