Only 2 boards Hashing on S7

[mcfly1982]

Can anyone help me please? Im pretty new to Antminers and am having issues. I bought this S7 nearly a year ago and since I have had it only 2 boards have been hashing. The person I bought it from hasn't been that helpful and now too much time has gone by to be able to send it back etc.

So to start with I thought it had a dodgy board so sent it to Bitmain who advise it was fine.

So one by one I can get the board to hash. Have tested each connection cable to each board and they all work fine. Have tested each connection point with each board and cable and all seems fine, however as son as i connect all 3 boards up, only 2 will ever work.

Can the connection board be faulty? Could it be something else?

Can anyone help me please? I have no idea what else to do and has been going on for so long now.

[NotFuzzyWarm]

An s7 will consume between 1,250-1,350w of power. Can your PSU support that? I suspect it cannot.

[mcfly1982]

I have 2 x 750's running it so don't think it's a power issue.

[NotFuzzyWarm]

I have 2 x 750's running it so don't think it's a power issue.

Actually - yes it is. Each hash board takes ~450w so that means that one supply is being overloaded. I would suspect that the board dropping out is usually one of the 2 being fed from 1 supply?

And do not even think about 1 hash board sharing the 2 supplies -- THAT IS A VERY FAST WAY TO KILL A PSU as each shared supply fights the other to keep a steady voltage.

[mcfly1982]

Oh, I was advised that that set up would work. I can try adding a third to it so 1 PSU per board. On that set up, so I power up the 2 boards that are not connected to the main board first and then the third one.
Hadn't thought about that being an issue so hope you are correct.
Thanks.

[NotFuzzyWarm]

In the manuals for ALL of their miners they make very explicit mention about using multiple PSU's. #1 on their list for using smaller PSU's is only 1-per hashboard due to the issue I mentioned.

[mcfly1982]

Hi, ok I have an old S2 so have taken the PSU from that and added it but still only 2 boards Hash.
so to confirm, each board has its own PSU but still only 2 hash.
Any other ideas?

[NotFuzzyWarm]

So one by one I can get the board to hash. Have tested each connection cable to each board and they all work fine. Have tested each connection point with each board and cable and all seems fine, however as son as i connect all 3 boards up, only 2 will ever work.

Okay...
Being rated >1kw a s2 PSU will be able to support 2 hash boards assuming there are enough PCIe plugs on it.

This still usually points to a power issue. Other than asking if you have a voltmeter to actually measure voltage at the PCIe plugs, since you tried using a 3rd PSU in it for now we'll set that thought aside.

Is it the same board that fails each time?

[mcfly1982]

Hi, no it appears to be different depending on which port I plug the boards into. There doesn't seem to be a pattern really.

[NotFuzzyWarm]

Okay, any idea what batch# it is? Or more to the point - are all the cards in from the same batch. Different ones run at different speeds. Somewhere on the Forum there is a chart of batch#/speeds. As I recall also info about it on Bitmains site.

What MHz speed you running at? Tried slowing it down?

[fanatic26]

Each hash card should have a sticker on the back side (small heatsink side) that says something like 45#700 referencing the chip count and stock speed. There are also stickers that should have the order number on each board so you can verify they are the three original cards from that system.

If it is not a power issue im thinking its a controller issue. Not an issue with the beagle bone itself but with the control board where everything plugs into.


Also posting the kernel log would be helpful in troubleshooting this issue.

[mcfly1982]

ok, 2 of the cards have
1385+ bin3 and bin1
one doesnt.
Currently board 2 is the one not hashing and that is bin3.
The frequency is set 600.
Kernal log page is blank.
Should i try a different controller board?

[mcfly1982]

Shall i just buy the data board then? Are they easy to swap out?

[fanatic26]

The control board is what I would say is having issues. It is an easy swap, 4 screws to take the controller/housing off, then 4 more to separate it from the housing.

[mcfly1982]

Anyone know where i can purchase one in the UK?

[beltsniffer]

Anyone know where i can purchase one in the UK?

Probably best to buy them directly from Bitmain here:
https://shop.bitmain.com/part.htm

Or Bitmain Warranty. If I remember correctly they have a shop in Iceland.
https://bitmainwarranty.com/product-category/products/