[Antminer S1] - Pencil Voltage Mod guide

GenTarkin

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Quote from: jacob019 on March 21, 2014, 09:28:06 AM

Nice work GenTarkin!

Really interested in undervolting to the extend the useful life of our S1's down the road.

1. Would increasing the resistance at R12 have the desired effect?
2. How far can we go?
3. How did you calculate the resistance target?

Ive not tried undervolting but theres a thread where someone is going to do that w/ the R12 resistor =) They are gonna attempt .75v @ 200mhz or so ... iirc'

I didnt calculate resistance really, I just dropped the resistance about 1k at first on the R3 using a pencil and then booting the antminer up and measurig ASIC voltage.
Based on that result, I further experimented w/ more & less resistance accordingly.

jacob019

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Cryptomancer

Nice work GenTarkin!

Really interested in undervolting to the extend the useful life of our S1's down the road.

1. Would increasing the resistance at R12 have the desired effect?
2. How far can we go?
3. How did you calculate the resistance target?

GenTarkin

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Also, Im wondering, what exactly draws the current on that particular buck regulator. Just the ASIC chips VDD? because, if so, at 1.1v the (x8) ASICs draw far less than 30A on their VDD, and based on the increase of Amps shown in the datasheet, figuring 1.2v would put the (x8) chips @ 3.9A or so, would only draw just above 30A

GenTarkin

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Quote from: jimrome on March 20, 2014, 07:37:46 PM

Quote from: GenTarkin on March 20, 2014, 04:27:36 PM

... the avg voltage has climbed to 1.17v on all chips - think theres a settling period or something..

You're very likely seeing the resistance of the pencil carbon change as it warms and cools. Once you've established the ideal nominal resistance you might want to replace the resistor/pencil for temperature stable resistors. Could also just be carbon flaking off?

As far as overloading the parts is concerned, that little buck regulator is only rated to ~30A, but is capable of supplying much more (core is rated to 40A IIRC). It has built-in thermal protection so the chances of frying it are low - instead of smoke you would instead have thermal shutdowns until the temp returns to 'safe' level.

These shutdowns can be mitigated or even avoided if heat sinks are applied to the back side of the regulator, (which is on the back side of the PCBs obviously). We did this pretty extensively when modding bitfury boards, which use the same part: https://bitcointalksearch.org/topic/m.3152210

Thanks for the informative post! ... been looking for an answer like this regarding that IC
I figured its current handling capabilities were more closely dependent on the temperature it reached.

jimrome

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Quote from: GenTarkin on March 20, 2014, 04:27:36 PM

... the avg voltage has climbed to 1.17v on all chips - think theres a settling period or something..

You're very likely seeing the resistance of the pencil carbon change as it warms and cools. Once you've established the ideal nominal resistance you might want to replace the resistor/pencil for temperature stable resistors. Could also just be carbon flaking off?

As far as overloading the parts is concerned, that little buck regulator is only rated to ~30A, but is capable of supplying much more (core is rated to 40A IIRC). It has built-in thermal protection so the chances of frying it are low - instead of smoke you would instead have thermal shutdowns until the temp returns to 'safe' level.

These shutdowns can be mitigated or even avoided if heat sinks are applied to the back side of the regulator, (which is on the back side of the PCBs obviously). We did this pretty extensively when modding bitfury boards, which use the same part: https://bitcointalksearch.org/topic/m.3152210

tacotime

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gmaxwell was the one who mentioned it to me, if you can track him down you might be able to figure out which components you might need to replace.

GenTarkin

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Quote from: tacotime on March 20, 2014, 05:17:00 PM

I wouldn't super be into pencil modding these, a bunch of the components involved in voltage regulation are already overloaded about four fold at stock voltage.

Four fold? I highly doubt that, otherwise shit would be on fire. They are over spec a bit ... but seem to tolerate it fine and components absolute maximum power output, like the main IC for the VRM ..., is nowhere near its maximum.

But as far as capacitors and shit, I have no idea =P

tacotime

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I wouldn't super be into pencil modding these, a bunch of the components involved in voltage regulation are already overloaded about four fold at stock voltage.

GenTarkin

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BTW, just an update after a few days, the antminer is still goin strong, avging 213GH @ 418mhz @ .31 %HW ... the avg voltage has climbed to 1.17v on all chips - think theres a settling period or something..

GenTarkin

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Quote from: ?? on ??

no pics?

Not for now, 2 reasons:
1, Im lazy
2, I figure if people cant look at the PCB schematics or the PCB directly and find the components themselves then....its probably too dangerous for them to even attempt this in the first place.

GenTarkin

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Quote from: the-skeptic on March 16, 2014, 08:39:31 PM

Note: Not all pencils are created equal. A generic #2 pencil from Office Depot wouldn't get the voltage over 1.13 volts. A good ole' fat construction pencil from Home Depot worked much better for me.

Remember to always test the first cap (C17, I think), because it will show the highest voltage, in case you over-pencil it.

As far as my experience: I have 6 S1 Antminers, and none of them like the 418 MHz setting. HWE rates were 4.5% - 5.3% with hash rates around 210 GHs even with the pencil mod. At 393 MHz (5f05, 36) I was getting .85% - .90% HWE before the pencil mod, but the mod actually lowered it to .45% - .51% across the board. Hashrate has remained at 200 GHs. I don't have a killawatt, so I have no idea on consumption.

edit:to the OP, what firmware do you run?

I run the newest firmware. Also, I pencil mod w/ a cheap #2 pencil thats like 15+ years old ... took to the voltage up to 1.3v on a module at power on ... while I was experimenting =P
The resistance on R3 dropped to somehing like 3.5k...

What build date are ur antminers? Ive only tried it on the 2013 december antminer.... wonder if it doesnt work as well on 2014 antminers. What voltage were you setting urs to for the 418mhz setting?

Also, cap C4 is the highest voltage cap before it gets to the ASICs ... this is is more representative of the voltage being pushed by the VRM IC, to the ASICs
For easiness sake, I do measure C17 rather than C4 tho =P

the-skeptic

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Note: Not all pencils are created equal. A generic #2 pencil from Office Depot wouldn't get the voltage over 1.13 volts. A good ole' fat construction pencil from Home Depot worked much better for me.

Remember to always test the first cap (C17, I think), because it will show the highest voltage, in case you over-pencil it.

As far as my experience: I have 6 S1 Antminers, and none of them like the 418 MHz setting. HWE rates were 4.5% - 5.3% with hash rates around 210 GHs even with the pencil mod. At 393 MHz (5f05, 36) I was getting .85% - .90% HWE before the pencil mod, but the mod actually lowered it to .45% - .51% across the board. Hashrate has remained at 200 GHs. I don't have a killawatt, so I have no idea on consumption.

edit:to the OP, what firmware do you run?

the-skeptic

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Quote from: GenTarkin on March 16, 2014, 02:52:00 PM

Quote from: matt4054 on March 16, 2014, 02:49:36 PM

In a couple of months (like diff x 4) it will be interesting to try to undervolt it and test max freq w/ decent HW error rate.

Yeah, I think to do undervolt, the resistor R3 (right next to R12) can be pencil modded ... this should theoretically drop the voltage.
R12 would not be pencil modded in this case.

careful with R3! The voltage on the first (left most) yellow cap jumps from 1.1v to 2.6v when pencil lead gets on R3. I haven't tried to boot a miner with the first cap being so high. It could lead to disaster.....

ZiG

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Yep..."Time IS Money"...in that business...literally...

GenTarkin

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Quote from: ZiG on March 16, 2014, 02:59:51 PM

Super, GenTarkin...!

What is your cooling...Did you upgrade it...?

Stock cooling, for now Im in a semi cool environment, so no need to uprade it. When summer comes, may have to undo the mod =(
I wish I woulda thought bout figuring this out ... months ago .. =)

Littleshop

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Quote from: GenTarkin on March 16, 2014, 02:52:00 PM

Quote from: matt4054 on March 16, 2014, 02:49:36 PM

In a couple of months (like diff x 4) it will be interesting to try to undervolt it and test max freq w/ decent HW error rate.

Yeah, I think to do undervolt, the resistor R3 (right next to R12) can be pencil modded ... this should theoretically drop the voltage.
R12 would not be pencil modded in this case.

This sounds a little more interesting. If the power consumption can drop 25% but the hash rate maybe 10% that would give them a longer life in the future.

ZiG

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Super, GenTarkin...!

What is your cooling...Did you upgrade it...?

GenTarkin

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Quote from: the-skeptic on March 16, 2014, 02:49:56 PM

Quote from: GenTarkin on March 16, 2014, 02:47:07 PM

A quick update, 16hrs later, shes still running strong.
418mhz, .8% HW, 212.3GH MHSav

Using an 80% effecient PSU ... power draw from wall - 510w

What are your OC settings, hex and timeout for 418?

418mhz = 6105
timeout I have set to 33

GenTarkin

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Quote from: matt4054 on March 16, 2014, 02:49:36 PM

In a couple of months (like diff x 4) it will be interesting to try to undervolt it and test max freq w/ decent HW error rate.

Yeah, I think to do undervolt, the resistor R3 (right next to R12) can be pencil modded ... this should theoretically drop the voltage.
R12 would not be pencil modded in this case.

sikke

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Quote from: GenTarkin on March 16, 2014, 02:47:07 PM

A quick update, 16hrs later, shes still running strong.
418mhz, .8% HW, 212.3GH MHSav

Using an 80% effecient PSU ... power draw from wall - 510w

This is impressive. Some of us ignore the powerdrawn and only want GH/s
I already have 1 selected good performer unit that does 205GH to pool with low HW at 400mhz. All my other units have been under 200Gh at pool.

I will start same test with my special unit Roll Eyes

Topic: [Antminer S1] - Pencil Voltage Mod guide (Read 5556 times)