For those who put a second fan in front:
I picked up a few different fans to try: Arctic F12 can only be installed in one direction (push, not pull), Enermax has four pins connector, but connector has two small plastic rails which prevent the connector to fit pins (I did not try to push it hard yet) and Corsair air SP120 has just 3 pins, so no PWM. Anybody had trouble with fitting regular fans connectors with Ants pins? Did the second fan in front even helped?
I use a few Akasa AK-FN073. It also has 2 of the plastic rails... 1 in the middle which would break the plastic backplate of the connector (on the ant).
I removed the plastic rail in the middle with a sharp knive and problem solved!
I think that a normal fan would be better than a PWM... because as soon as the temp drops on the rear side of the ant... the front fan slows in rotations in order to stay at the programmed temp by bitmain. Personally I haven't bothered buying other fans for my latest 3 ants..