The most I can get out of my two Batch 2 machines is 687 (although 681 produces a higher hashrate) and 625. Anything over that and the third hashboard on both machines goes to 0 hashrate.
i just recived my 2nd batch. mine too. 3rd chain die at 681 or up.
What hash rate are you getting at 681 or close. Do you get hw errors on any chains or does it just hash at 0 when you go at or over 681
same here... what about flashing the may 2018 firmware on to it?.... my batch 1 runs fine at 750..17 sols batch 2 one board dies above 675 freq.. 14 sols...
I'm wondering if bitmain hasn't cherry picked hashboards for the Z9s over the minis in this batch?
In theory I'll have a Z9 next week to see how (if?) it overclocks.
I wouldn't imagine their yield suddenly going down across the board on OC stability.
Just noticed Bitmains support page has a firmware upgrade for the Z9 that changes the frequency from 500 to 550...so no overclocking i guess?
https://service.bitmain.com/support/download?product=Antminer%20Z9
Edit: and the manual states it has a fixed frequency of 500 Mhz