I just set mine to low. Setting it to Hi, does not affect my CPU temps at all. If you have a hot chipset or video, then you should consider hi, and just leave it at that.
The top fan control cable is tied with my PSU 4pin CPU cable. The rear fan was just swung across the my chipset cooler. I recently replaced the rear fan with a 3pin 120mm fan, and just attached it to the motherboard.
It's too bad, because I have the P182 and that has the fan controls mounted on the case, in the rear so you can access it easily.