The 2nd-hand R4 control board has entire add-ons and can be used Typically after getting the goods. Welcome All people to order with self esteem. There are actually a complete of 30 BM1397 chips on the whole board. These are dispersed beneath the entrance heatsink and connected to the heatsink https://damienamucj.widblog.com/92201177/5-simple-statements-about-antminer-s21-control-board-explained