3A 2.5A Max (24AWG wire is required to meet this current rating), the stock fan use 1.75A and we have 6A fuse

Pinout:
1 - 12V
2 - GND
3 - TACHO (Fan output towards controller board for rotation indication)
4 - PWM (controller board output towards fan to set rotation speed)

If you mod the stock fan, you'll loose warranty of course.

Guy