[Antminer S9] How does the S9 know what hashrate to "autotune" to?

[tim-bc]

So this is a question that I've been wondering about for a while, but now I am even more motivated to find the answer due to the recent release of the "Low Power Mode" firmware from bitmain, which is autotune and doesn't seem to have a fixed frequency option.

The question is, how does the S9 know what its hashrate is supposed to be? For example, I took one S9_13.5T and one S9_14.0T and flashed the Antminer-S9-LPM-20181023.tar.gz to both. Afterwards, the S9_13.5T still "autotuned" to 13.5 THs, same with the 14.0T.

I was under the impression that flashing a new firmware overwrote the old filesystem. How then is it possible for the S9 to "remember" its assigned hashrate? Where is this value stored, and how can we change it?

It would be great if we could "autotune" the S9 to 15 TH while it is on the "Low Power Mode" autotune firmware. I'm mainly only familiar with the fixed frequency firmwares / bmminers so I would really appreciate any insight into how the "autotune" firmwares work. Thanks!


By its assigned hashrate, I am referring to the "fixed rate" displayed in the log:

S9_13.5T after flash:

Code:

miner total rate=13772GH/s fixed rate=13500GH/s

S9_14.0T after flash:

Code:

miner total rate=14014GH/s fixed rate=14000GH/s

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[fanatic26_]

There is a chip on each hashboard that identifies what it is to the controller

[tim-bc]

There is a chip on each hashboard that identifies what it is to the controller

Thanks! I tested and confirmed this just to make sure.

Do you know if there's any way to make a miner tune to a different hashrate? Or if there is a way to run the "Low Power Mode" firmware with a fixed frequency?

[ccgllc]

Do you know if there's any way to make a miner tune to a different hashrate? Or if there is a way to run the "Low Power Mode" firmware with a fixed frequency?

Back flash to the May 17 firmware, use the cgi-bin/minerAdvanced.cgi weblink to access the full speed menu and set it.

Flash forward to 1023.

[tim-bc]

Back flash to the May 17 firmware, use the cgi-bin/minerAdvanced.cgi weblink to access the full speed menu and set it.

Flash forward to 1023.

If you upgrade a fixed frequency miner with the new firmware package will it stay on fixed freq? I thought it was autofreq which would disregard the frequency setting from minerAdvanced.cgi. I'll have to try it tomorrow.

[tim-bc]

Cool! It turns out if you flash the low power file onto a miner with fixed frequency it will not override it to autofreq. Dunno why I didn't think to try that. Thanks everyone!