the fan ports on you motherboard have 3 pins... because 1 is for power, 1 is for ground and the last is to monitor Fan speed.
You dont need 3 wires to connect a fan to it, you just cant read fan speed if your fan only has 2 wires....
Your sapost to plug the CPU fan into the Fan1 connector (usually located closest to the CPU itself) because the bios monitors CPU fan speed and adjusts it acordingly...
however if your fan has no speed sensor, it will probably just run at max, so tecnically it probably doesnt matter were you connect it.... but (not shur if its AMD or Intel) but some boards wont boot unless you have a fan connected to the CPU Fan1 port.