"String" or "Module" refers to the way the Chips are powered. Might be better to think of it as Series or Parallel. In the S1 & S3 the chips are powered in Parallel. In practice it is slightly more complex with the 12V powering a number of Buck Converters that drop the 12V to the voltage required for the Core (0.7V -1.0V) Each Buck Converter then powers a number of chips, 8 in the S1 and 2 in the S3.
In the S5 & S7 the chips power is connected in Series (Just like old style Christmas Tree Lights) So in the case of the S5 there are 15 pairs of chips in the chain, 12V /15 = 0.8V / chip. All very neat and efficient as there are no Buck Converters needed, saves money and is very efficient, But....
If one of the chips in the chain fails then at best you loose all the chips after that one and often you loose the whole chain, dependant on the failure mode. If a chip goes open circuit (Like a bulb blowing in the Christmas Lights) as the voltages to the chips are messed.
Also worth remembering that as well as the power all of the data & control signals in all of the Miners is chained through the chips. It seems that sometimes even if a chip is not hashing it continues to pass through these signals enabling the chips further down to keep operating , however with more major failures downstream chips will stop working.
Rich
In the S5 & S7 the chips power is connected in Series (Just like old style Christmas Tree Lights) So in the case of the S5 there are 15 pairs of chips in the chain, 12V /15 = 0.8V / chip. All very neat and efficient as there are no Buck Converters needed, saves money and is very efficient, But....
If one of the chips in the chain fails then at best you loose all the chips after that one and often you loose the whole chain, dependant on the failure mode. If a chip goes open circuit (Like a bulb blowing in the Christmas Lights) as the voltages to the chips are messed.
Also worth remembering that as well as the power all of the data & control signals in all of the Miners is chained through the chips. It seems that sometimes even if a chip is not hashing it continues to pass through these signals enabling the chips further down to keep operating , however with more major failures downstream chips will stop working.
Rich
It would be interesting to see a design based on rectified and smoothed 120V. No external PSU needed
Just as an aside on the Christmas lights, I have those ones where a dead bulb does not kill the lights. Problem is, it does that by shorting the connection through the bulb, leading to increased voltage to the other bulbs and more rapid failure. By the time you get to three dead bulbs in a row, it's game-over for that segment. Not sure this is relevant but I felt like sharing
If you rectified & smoothed 120V Mains would give 168V. You are going to need a very long string, like 210 Chips. Could be done but the strings work better with more than one chip at each stage. S5 has 2, S7 has 3. So that means 420 or 660 so not very practical, and without an isolating transformer, which will have losses, not very safe.
Yes the bulb failure mode you describe can also happen in a Miner if a chip goes short circuit...
Rich
