I have one S5 that is guaranteed to give me:
oooo first line all the way across
second line xxooooooo
Lower clock and soft boot corrects it on reboot sometimes.
Hard boot almost always corrects it.
Either correction, lasts 5 mins to a couple of hours
A severe underclock will correct it for the longest time, hours, maybe more depending on how low.
Checked connections
I have not swapped any parts yet.
My money is on the second / right hash board, but I understand it could be the controller or cable.
Simple, good information provided by Bitmain at their zendesk site:
https://bitmain.zendesk.com/hc/en-us/articles/204875015-How-to-diagnose-S5-hashing-PCBSome people may find it useful to pull these down locally and grab one when needed.
It never hurts to remind experienced brains.
A side note:
Bitmain has a quick video giving the steps to address these types of issues quickly. Props for doing so to Bitmain.
I want to make sure I show I have affection for Bitmain's good points as well. I hope to always discuss the good and bad regarding the choices of miners.
**--If you find incorrect information in the videos which you think are serious enough to require discussion please post me a PM about them and maybe we can make a new thread somewhere. I have not vetted every inch of material by any means. Use your common sense and be safe. -period- and if possible be more safe with live power. Do not work with live power unless it is necessary. Personally, I do not think it makes anyone look cool because they worked with blah blah volts times amps. Why would you want to? It isn't on my list of goals to work with hot high amounts of anything which will kill me, but I tolerate the 120 / 240 / 480 pretty well.
If you do not understand everywhere the power may flow, do not change a circuit, install a breaker, or in general don't do anything but look, take pictures, and write things down at your main panel without some qualified help. Give the forum some details about your rig and people will be happy to give you many great suggestions on your S7 with a wide variety of side products and options.
If you do not understand where the power will flow when you flip the breaker / switch, or circuit on, then have someone qualified, even if you must pay. Start reading and practicing small time. Learn how to respect power even if you aren't interested in learning everything about it.