undervolt antminer s3

[miguportugal]

hello

iam want to undervolt my antminer s3

i was reading in the datsheet

 Typical hash rate and power
Voltage(V) HashRate(GH/s) Current(A) Total power(W)  W/GH
0.72          14.18                10.40          7.49                0.528
0.75          15.75                12.24          9.18                0.583
0.80          17.33                15.20          12.16              0.702
0.85          17.33                20.00          17.00              0.981

can someone help to modify my s3 to set the voltage to 0,72v

[philipma1957]

as of today i have yet to see a thread on how to under-volt an s-3

[miguportugal]

i have some antminer s3

but i only have 3000W to mining

i need to have max efficiency

[guitarplinker]

How many S3's are you running? You should be able to run 8 at stock speeds with 3kW.

[miguportugal]

i have s3 and s1

maybe undervolt we can achieve 200w to 370gh/s

i just need to kmow the  wright resistor to change value

[philipma1957]

i have s3 and s1

maybe undervolt we can achieve 200w to 370gh/s

i just need to kmow the  wright resistor to change value

I think if people have figured it out they are not as willing to share the info as they were with the s-1.

things are very tight with miners.  If you could get .6 watts vs .8 watts for - s3's it would be wroth a lot.

my self I purchased some am tubes.  I sold off 4 of my 6 s-3's .  I made about .3 btc a miner.  used the profits to buy the tubes.  maybe some one will show s-3's doing .6watts but I do not count on it.

[RayJay]

That chart seams to be purely theoretical, or may been results of the chip design simulation.

I did a whole batch of undervolting my S3 to different voltages trying to replicate the efficenty in the chart.
At 0.72v the max clock could not be higher than 193Mhz and resulted in 380GH/s at 280w on the wall. That's only 20w improvement over the unmodified voltage ( 300w at 380GH/s )
The gain by undervolting is not comparable to the S1 where you could get almost twice the efficency with a careful pencil mod.
Although for me it was still worth it, because of my power restrictions and heat problems in my small apartment.
Without intend trying to keep the max GH/s In mind I found my sweet spot at 150MHz clock rate and 0.68-0.69v producing 310GH/s at 180w on the wall.
Also I really wanted to get the consumption per S3 below 200w to be able to use a single PCIE power cable per unit so I can have all 6x S3's running of only one 1500w SilverStone PSU.
The end result is 1.8-1.9 TH/s at 1100w on the wall (80plus Gold PSU) which is still only 0.6w per GH.
So that may be one of the reasons why ther is no "official" S3 pencil mod. It's simply not worth the trouble.
In my case it was more about the power restriction and heat output. Which is now more like a warm breeze on the fan exhaust rather than standing in front of a space heater on max in my small Texas heat 625 sqft Apartment. As nice side effect the fan noise is a lot less now (from 2100-2400 rpm Down to 1000 rpm). With some F12 fan replacements I could make the S3 completely silent now.
The mod is a big hassle and very tricky with the having to remove the case and boards. The location of the resistors ( on the inside/back of the board ) is also tricky to work with.
And the PCB seams to be very fragile, I managed to kil two boards. I barly touched the board and yanked off a tiny capacitor this was sticking out from the board. After carefull soldering I tought I fixed it but must have shorted something and resulted in a dead board. Even only one bad voltage regulator ( 1 of 8 per board ) results on a completely dead board.

I made plenty of pictures during the mod, but I feel the gain in efficency and General PITA to do the mod is not worth the write for a tutorial.

-Jay

[miguportugal]

can you explain better, i want to try with 0,65v

[RayJay]

0.68v seams to be the physical limit of the chips ( at 150Mhz clock ). A little lower and you get all hardware errors.

[neegeeboo]

Rayjay,  can you please share the freq value and timeout setting you're using at .68v?  Also, just to confirm, you're not using to pencil mod to get this to work?

I'm limited to 20amp of power and would like to get as many s3 as possible on a 20amp circuit.

[RayJay]

I used the new firmware with the "Advanced" tab to adjust the clock frequency down to 150mhz, with that the consumption goes down to 240-250w on the wall ( at 310 Gh/s ).
The resistors are located on the back, or the inside where the big sink is attached. You will need to completely remove the board to get proper access to the resistors.
The default value is 2.083 Kohm. And I use the pencil mod to bring the value down to 0.900 to 1.050 Kohm. I have most of mine set close to 0.950 Kohm.
After that the consumption will be down to 180w on the wall ( still at 310 Gh/s ). Noise from the fans and temp will be way down after this mod. And you can use a single PCIE cable to power one S3 ( two hashing boards )

[philipma1957]

I used the new firmware with the "Advanced" tab to adjust the clock frequency down to 150mhz, with that the consumption goes down to 240-250w on the wall ( at 310 Gh/s ).
The resistors are located on the back, or the inside where the big sink is attached. You will need to completely remove the board to get proper access to the resistors.
The default value is 2.083 Kohm. And I use the pencil mod to bring the value down to 0.900 to 1.050 Kohm. I have most of mine set close to 0.950 Kohm.
After that the consumption will be down to 180w on the wall ( still at 310 Gh/s ). Noise from the fans and temp will be way down after this mod. And you can use a single PCIE cable to power one S3 ( two hashing boards )

so 180/310 =  .58 watts   at freq clock 150

if I do advanced tab now at freq clock 200 and 400 gh  just a down clock I get   333watts  so that is 333/400 =  .83 watts

  frankly  I would be tempted to do this. as I could run 6 s-3 on 1 evga 1300  

 6 x 180 = 1080 watts  and get 1860 gh

could you post photos of the resistor to be pencil modded.

@ neegeeboo

setting for 150 are

  #option 'freq_value'    '0b83'  #150M
  #option 'chip_freq'     '150'
  #option 'timeout'       '27'                feel free to try 26 or 28

[RayJay]

Hi Phillip,
Correct, I run 6x S3 at 150Mhz undervolted at exactly 1090w on the wall (GHash.io reports a 1.85 TH/s dally total ). Not sure if 200 watts headroom is save ( I think your suppose to stay 25% under the maximum rating at continues usage ).

I tried undervolting 193MHz-200Mhz but it only yielded 380Gh/s at 280w was not worth it in my opinion. ( the gain was only 20w ) and noise and heat was not much lower.

If you shot me your email in a pm I canemail you some photos and simple instructions. If you done a S1 pencil mod you should be fine, but if not it might be a little more you bargaind for.

[philipma1957]

sent pm.

i did the s-1's i would do the s-3's

[RayJay]

The S3 uses similar blades like the s1 right? Theoretically could we just pop off the case, pencil mod it and do the same thing as we did to the s1 and change freq?

Yes they look very similar, the man difference is that you have to take the S3 pretty much completely apart.
You have to get access to the back side of the blades since the resistors ar on the back not in the front like on the S1. So just popping of the case won't be enough.

[philipma1957]

well I have 6 of them so I would be willing to tear one down.

[SEGMining]

I am very interested in this topic.

[82kevin]

With the new antMiner_S320141013 update on Bitmain's website you can easily modify the voltage under "miner configuration" then "advanced settings". I have played around with .63v but I get more hw than I would like. A voltage of .72v at 243.7mhz gives me a solid 490gh/s while using about the same wattage as stock.

[neegeeboo]

With the new antMiner_S320141013 update on Bitmain's website you can easily modify the voltage under "miner configuration" then "advanced settings". I have played around with .63v but I get more hw than I would like. A voltage of .72v at 243.7mhz gives me a solid 490gh/s while using about the same wattage as stock.

Are you doing this with the s3 or s3+?  Do you know if there is a difference?

[bernard75]

With the new antMiner_S320141013 update on Bitmain's website you can easily modify the voltage under "miner configuration" then "advanced settings". I have played around with .63v but I get more hw than I would like. A voltage of .72v at 243.7mhz gives me a solid 490gh/s while using about the same wattage as stock.

Are you doing this with the s3 or s3+?  Do you know if there is a difference?

Nope, there isnt.