My GH/S(avg) decreased from 12,600 to 11,400 due to several "x" on one hashing board. Moreover, this board does not have GH/S(RT) indicated. I restated the miner by disconnect the power a lot of times but it won't help. Does anybody have the same problem? What is your experiance with the bitmain warranty?

This is the screenshot.
https://imgur.com/a/y0VQk