Whatsminer M21B PSU data cable is used to connect the control board and the power supply, and its function is to supply power to the control board. It is a double-ended 2*9 18P 22cm cable. Please note that the buckles must correspond to each other when using this data cable to connect the control board and the power supply. If it is reversed or wrongly inserted, the control board may be burned when the power is turned on!