Just throw a reminder here to power the control board after the hash boards are up if possible.
The bitmain wording was recently changed to something more along the lines of apply power to the power supply feeding the hash boards first, and then the control board.
Many have suggested this has to do with the issues people are seeing with low hashrates.
Personally, I follow their instructions to the letter, and even to the point of using a different power supply to power my control board on my S5+ so there is no doubt about my hash boards being powered first. I am not wasting the leftover power on the power supply I use on the control board, as I am also powering a couple of S5s from it was well.
To comment on the low hash people are experiencing where the soft boot seems to pickup, I have this exact same experience with some S3s where it is truly exaggerated behaviour. Literally a hard boot shows a hash rate of a few ghs, where a soft restart allows them to operate correctly. I have seen some of the same but not as bad behaviour with my S4s, and once I knew what to look for I see it with the S5 as well. I have no doubt there is an issue across the board which causes this scenario, but as for it being tied to when the control board is powered on, I cannot say. Whether this has to do with the S7 as well I cannot say as mine is late.
Good luck to you!
Have ONE s7.
I'm running it on one bitmain 1600 watt psu.
I'm going to try using two corsair rm1000 psu's with one on two hashboards and the other on one hashboard and the controller.
I'm going to fire up the controller psu first and then the 2 hashboard psu and see what it does.
Then I will do a soft reboot and see what THAT does.
Ok here we go.
I have a batch one running 575 as shipped.
Has been 4600 for days (5 or so)
Power on corsair with controller and one hashboard.
Wait 5 seconds
Power on corsair with two hashboards.
After 15 minutes 4600
Soft reboot
After 15 minutes 4600
I don't understand the hashboard first thing.
Maybe 15 or 30 second delay between power on?
I think there are two separate things being discussed.
1. There is an issue with the S7s where they will not hash higher than 4600 ish. It has been suggested that slightly low input power may cause this. I recommend checking your input load at the psu connection at the miner. If you are handy with a meter you may have meter leads with needle points and you may get in the back side of the connector, or, if you have a single going to a Y cable connecting to the miner, measure the unused end on the Y connector. Phillip shows pictures of this in a couple of threads and he has presented this theory regarding the voltage.
2. Phillip also brought up the fact that a soft restart may help this issue, and I believe it has for one or two people with the S7. I was commenting in this thread to the other gentleman that I have seen this issue with S3s where it is pronounced. IT is usually the worst if I have a quick power outage, just long enough for the miner to know it was off for a second. on some of the S3s it literally shows 3 or 4 ghs for the main average, not the 5s average, it usually shows a normal number for the 5s. I do a soft restart and it begins working correctly. I saw some of this with my S4s, but not the literal 4 or 4 GHS on hard boot, just poor performance until I performed a soft boot. The same with some S5s. I cannot say on the S7 as I am waiting.
3. Then of course the power on the hash boards before the controller. This is an instruction bitmain began passing with the S5+ and has now continued with the S7, but unfortunately we have been unable to get any clear indication from bitmain as to why so we understand their intent. In the latest statement I read, I cannot remember if it was their website or the S7 manual, but whichever states to the effect of if using multiple power supplies power on the hash board power supply first and then the power supply for the controller. The way it is worded it It didn't seem to be an issue if you happen to be powering hash boards and controller if it happens to be on one power supply, but if it is separate power on the controler last. I am sure their engineering team have a good reason for this, but because we have experienced issues with translation along with the fact bitmain has a poor record of communication we are left to theorize and try to interpret what they mean by these things.
I know my input power is strong to the power supplies, and to the miners, and I have no issues with #2 because I began seeing that issue with my first S3 purchases and have been soft start everything after a hard start anyway. Hell I like to be up close with my miners after I boot them. I have shortcuts setup to get me there quickly so I can look at everything. I'm a bit anal like that so it works.
I think your main point here would be to check what Phillipma mentioned regarding power at the pci connector to the miner.
Feel free to PM if I can help in any way.
I can tell you when I managed to get my shit numbers my pcie cords measure 11.69 volts .
when I unplugged and replugged every connector and used nine 2 plug cords did the soft reboot after the hard reboot my cords went to 11.96 volts vs 11.69 volts
my errors dropped to 0.015x vs 0.11xx and hash went to above 4800 with power used at 1200 watts.
So I really think you absolutely must know that your pcie cables are over 11.9 and not under 11.7 when under full load to be sure it is bitmaintech's fault.
I have been able to duplicate good hash at 11.9 or more volts after soft boot everytime
I have been able to get bad hash at 11.69 volts every time.
It is late and I am tired and showing on one machine is not good enough.
I am getting a batch two machine soon I will test it and see if I can manage to get it to do proper hashing with proper volts.
or if it fails to hash correctly with say 12.01 volts at the board and after a soft boot. I can use this psu
https://www.trcelectronics.com/ecomm/pdf/hrp600.pdf run 1 board and be sure of power to the boards. I can even go to 12.5 volts at load to see if it does proper hash
I truly suspect that this issue is a:
voltage problem and a soft reboot problem blending into lower then normal hash.
