I received my miner yesterday. I was hoping to overclock but even at the stock 410 I’m getting chip errors on the second and 3rd boards. I contacted bitmain support and their solution is to reduce to 400 and restart several times.  Even if I get the chip errors they say it’s ok as long as it’s stable and no further action is needed. What a load of BS. Brand new unit, ROI is already down the crapper and it can’t even run at the stock frequency.