Antminer S2 Underclock

[amarotica]

Hi guys, so I know it's not very profitable obviously but is it possible to underclock the antminer s2? From what I understand, you can change the frequency lower but you need to change the voltage too or not? I need help on the voltage part. Thanks!

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[Unacceptable]

Look through this thread  

https://bitcointalk.org/index.php?topic=515448.0

Another with good info:

https://bitcointalk.org/index.php?topic=1023047.0

[adaseb]

You can underclock it so its less heat/noise but the power consumption will always be fixed since you can't change the voltage

[Amph]

You can underclock it so its less heat/noise but the power consumption will always be fixed since you can't change the voltage

how the heat is reduced if there is the same wattage(you said the same consumption)? it does not make sense

[alh]

I have to agree with Amph here. If underclocking reduces the heat output, then the power draw has been reduced. Watts are Watts and it all ends up as heat one way or another.  It's also typical for a reduced clock frequency to end up with a reduced power draw. This is all standard ASIC "physics", nothing magic.

It is also true that in many/most ASIC designs a reduced frequency would operate correctly with a reduced voltage. If the manufacturer hasn't the provided a means to adjust voltage, or their design makes that impractical (e.g. a string design), then you don't get as much power savings by simply reducing the clock frequency.

[quakefiend420]

You can underclock it so its less heat/noise but the power consumption will always be fixed since you can't change the voltage

how the heat is reduced if there is the same wattage(you said the same consumption)? it does not make sense

Perhaps what he means to say is the efficiency(W/GH) will always be fixed, not the power consumption.

[adaseb]

You can underclock it so its less heat/noise but the power consumption will always be fixed since you can't change the voltage

how the heat is reduced if there is the same wattage(you said the same consumption)? it does not make sense

Perhaps what he means to say is the efficiency(W/GH) will always be fixed, not the power consumption.

Yes that's what I meant. The W/GH will always be fixed but the total watts will be lower along with the hashrate when underclocked.

[guitarplinker]

Yes that's what I meant. The W/GH will always be fixed but the total watts will be lower along with the hashrate when underclocked.

I don't think Antminers downclock like that, at least S1's didn't. The lower you downclocked an S1, the more efficient it became. (higher GH/W ratio) Inversely, the higher you clock, the more inefficient it becomes. Downclocking made a huge difference with S1's as well - it would run at 180GH/s @ 360W (2W/GH) by default, but by downclocking to 140GH/s it would only take 170W. (efficiency of 1.21W/GH)

So as long as the S2 downclocks the same as the S1, (which I fully expect) the S2's efficiency will increase as well.

[helipotte]

My understanding is that the S2 is fairly close to the maximum efficiency of the BM1380 ASIC.  Most likely there is not much more to be gained by underclocking.

1 watt per GH is about the best this chip can do.  Maybe .9 watt with some intensive tweaking of the voltages.  Would be very tedious for and S2.

[adaseb]

My understanding is that the S2 is fairly close to the maximum efficiency of the BM1380 ASIC.  Most likely there is not much more to be gained by underclocking.

1 watt per GH is about the best this chip can do.  Maybe .9 watt with some intensive tweaking of the voltages.  Would be very tedious for and S2.

The voltage's can't be altered however. THere is no option in the settings.

[helipotte]

My understanding is that the S2 is fairly close to the maximum efficiency of the BM1380 ASIC.  Most likely there is not much more to be gained by underclocking.

1 watt per GH is about the best this chip can do.  Maybe .9 watt with some intensive tweaking of the voltages.  Would be very tedious for and S2.

The voltage's can't be altered however. THere is no option in the settings.

You have to "manually" tweak via pencil modding.  You add resistance to a feedback circuit in the regulator, hence lowering the voltage.  Would have to do this

40 times in the case of a S2.  With the S1, only 8 times.  This is why it would be tedious.

[sidehack]

Actually, you reduce resistance. I haven't tested on an S2, but based on my tests on the S1 it should be possible to get 0.8W/GH out of them, board-level.

[Meech]

If I have time this weekend I will give it a shot.  They're just gathering dust right now anyways.

[dimke_yu]

It would be nice to see how it performs below default clock... Please post settings and firmware that you are running...

[kano]

I've put up a new master cgminer AntS2 firmware in my cgminer-binaries git
of current git cgminer 4.9.1+ modified from the last Bitmain firmware 29-Oct-2014 and including all the changes I did last year
https://github.com/kanoi/cgminer-binaries/tree/master/AntS2

It includes a half speed half power setting in the Miner Configuration->Advanced Settings tab ... which isn't really all that useful, but shows that you probably wont get a better W/GHs lowering it, without hardware changes.

[adaseb]

Just wondering if anyone has tried here to undervolt/underclock their S2 yet?

[RichBC]

Not sure if the S2 has been done, but a lot of people have done the "Pencil Mod" on the S1, as is said above you have a 40 resistors to modify so a big job. If you search on S1 & pencil Mod you will find plenty of information.

Rich

[adaseb]

Not sure if the S2 has been done, but a lot of people have done the "Pencil Mod" on the S1, as is said above you have a 40 resistors to modify so a big job. If you search on S1 & pencil Mod you will find plenty of information.

Rich

I did but the layout is slightly different and there is no schematic online.

[adaseb]

Right so I have found the correct resistor and managed to get it downvolted to 0.70-0.71Volts from the original 0.75 V.

However its very hard to get it to run stable. At 196 Mhz half of the chips were getting X's.

So I downclocked the frequency to 163Mhz, it hashes but getting lots of rejections and 2% HW errors.

[RichBC]

Well done on finding the resistors. In some ways it's quite simple... If the voltage is too low for the frequency you will get too Many HW errors. So you either turn the frequency down some more until they become acceptable or you have to use an eraser on the resistors and redo them with less pencil and a higher voltage.

Have you just done a single board as an experiment or all of them? Also worth rechecking all the voltages if just one of them is too low than that one can cause the HW errors.

Rich