Toomim Bros received five Batch 1 S9s today. ... two ("m6" and "m8") gave low hashrates when run at 650 MHz, around 8 TH/s each....
to keep on topic: I wonder if the hash rate issues jtoomim is experiencing are heat related? It seems possible as the hash rates came up when the clock rate was decreased.
Unlikely, as the intake air temperatures have been between 8°C and 20°C while we saw problems. I can't be sure, but it almost seemed like we were having more trouble with the unit at night (8-10°C intake) than during the day.
Probably that, or core voltage as too low. Might have had some under-spec chips on those boards.
This sounds more plausible to me. In particular, I suspect an issue during the startup routine for the ASICs. The hashrate stays pretty stable over time as long as I don't restart cgminer, but restarting cgminer even with the same settings can cause the rig to gain or lose a few TH/s. I suspect that some of the strings might be having an issue during startup, causing about half of the ASICs on a hashboard to not hash.