[Hands On] Bitmain AntMiner S7 - Batch 8 - Notlist3d

[RadekG]

Anybody tried to adjust voltage on buck converter of S7B8? Still waiting for my piece. Maybe another pencil hack will do the trick?

I am considering to undervolt to keep noise below certain level...

[RichBC]

Anybody tried to adjust voltage on buck converter of S7B8? Still waiting for my piece. Maybe another pencil hack will do the trick?

I am considering to undervolt to keep noise below certain level...

A mod of some sort will be possible, but we need to fully understand exactly how they are using the Buck Converter & Digital Pot first.

Rich

[yslyung]

Anybody tried to adjust voltage on buck converter of S7B8? Still waiting for my piece. Maybe another pencil hack will do the trick?

I am considering to undervolt to keep noise below certain level...

underclcok it down to 100M sure quiet.

[RadekG]

Anybody tried to adjust voltage on buck converter of S7B8? Still waiting for my piece. Maybe another pencil hack will do the trick?

I am considering to undervolt to keep noise below certain level...

A mod of some sort will be possible, but we need to fully understand exactly how they are using the Buck Converter & Digital Pot first.

Rich

So, there is digital pot or digital dc-dc as seen in C1? So if it is digital, we may be able to controll it via SW or resistor VID settings?

[RichBC]

Anybody tried to adjust voltage on buck converter of S7B8? Still waiting for my piece. Maybe another pencil hack will do the trick?

I am considering to undervolt to keep noise below certain level...

A mod of some sort will be possible, but we need to fully understand exactly how they are using the Buck Converter & Digital Pot first.

Rich

So, there is digital pot or digital dc-dc as seen in C1? So if it is digital, we may be able to controll it via SW or resistor VID settings?

There is a PIC Microcontroller and a Digital pot controlling the Fb ground resistor. What is unknown at the moment is if this arrangement is tied into the main Controller in any way or if it is stand alone and either factory pre-set (most likely) or monitoring some parameter and adjusting accordingly?

I do not own a Batch 8 S7 so can run no checks, most likely that will be done by J4bberwock in the New year?

I won't have access to the S7 for the next 8-9 days, but I'll definitely change the 6k8 resistor as soon as I'm back.
800MHz, 5,3Th is still too low. I'm sure we can do 900.
And I'll probably try to get an earlier batch with 162 chips later to see how it can be overclocked.

Rich

[notlist3d]

The batch is doing well in the cold:

It's low 30's outside and that air is going into my mining area.  So far no issues with S7's with dealing with the cold.   It is safely where no water will effect I should mention to.

[RadekG]

There is a PIC Microcontroller and a Digital pot controlling the Fb ground resistor. What is unknown at the moment is if this arrangement is tied into the main Controller in any way or if it is stand alone and either factory pre-set (most likely) or monitoring some parameter and adjusting accordingly?

I do not own a Batch 8 S7 so can run no checks, most likely that will be done by J4bberwock in the New year?

I won't have access to the S7 for the next 8-9 days, but I'll definitely change the 6k8 resistor as soon as I'm back.
800MHz, 5,3Th is still too low. I'm sure we can do 900.
And I'll probably try to get an earlier batch with 162 chips later to see how it can be overclocked.

Rich

I will try to do my own investigation tomorrow, but C1 series had similar DC-DC and I think also with PIC. C1s DC-DC was very unreliable, some of them failed to set-up correct voltage and overvolted chips and shut down whole board. It is very strange as C1 DC-DC set-up voltage at 0.75V, but some voltage comands (after cgminer starts) result in wrong voltage setting. This happened over the time and some of blades can't set up even default 0.76V. Bitmain supplied "hot patch" by unsoldering buffer chip, so voltage stays at start-up level.
 

[RichBC]

I will try to do my own investigation tomorrow, but C1 series had similar DC-DC and I think also with PIC. C1s DC-DC was very unreliable, some of them failed to set-up correct voltage and overvolted chips and shut down whole board. It is very strange as C1 DC-DC set-up voltage at 0.75V, but some voltage comands (after cgminer starts) result in wrong voltage setting. This happened over the time and some of blades can't set up even default 0.76V. Bitmain supplied "hot patch" by unsoldering buffer chip, so voltage stays at start-up level.
 

It is because of this sort of problem that I suspect that Bitmain have gone for a factory set fixed voltage. it is however possible that they have chosen a different set voltage for Batch 6 v Batch 8/9?

One thing that keeps alive the possibility of a dynamic voltage setting is that if they had just wanted a factory set Core Voltage they could just have used an EE based digital pot with no PIC?

However anything is possible right up to a programmed selection of voltage dependant on the frequency selected? Some tests and measurements will be good.  


Rich

[notlist3d]

I will try to do my own investigation tomorrow, but C1 series had similar DC-DC and I think also with PIC. C1s DC-DC was very unreliable, some of them failed to set-up correct voltage and overvolted chips and shut down whole board. It is very strange as C1 DC-DC set-up voltage at 0.75V, but some voltage comands (after cgminer starts) result in wrong voltage setting. This happened over the time and some of blades can't set up even default 0.76V. Bitmain supplied "hot patch" by unsoldering buffer chip, so voltage stays at start-up level.
 

It is because of this sort of problem that I suspect that Bitmain have gone for a factory set fixed voltage. it is however possible that they have chosen a different set voltage for Batch 6 v Batch 8/9?

One thing that keeps alive the possibility of a dynamic voltage setting is that if they had just wanted a factory set Core Voltage they could just have used an EE based digital pot with no PIC?

However anything is possible right up to a programmed selection of voltage dependant on the frequency selected? Some tests and measurements will be good.  


Rich

Bitmain's official response would support your idea of factory set fixed voltage:

Got the official response back on efficiency:  "Currently, S7 is fixed with frequency to make sure the hash rate is more stable. but the voltage can be adjusted. The power consumption is 0.25 J/GH + 10% as marked in website."

So it appears the 4.7 is constant.  And that efficiency is the +10 marked in specs.

It's been a bit since they sent that to me.  But it did mention fixed frequency.

[tutorialevideo]

Did someone made some OC on the batch 8?

[klondike_bar]

I had a power outage.  The good new's is the S7 seemed to handle it great.  No issues from turning off in not the greatest way, and it booted up and worked fine after power was on.

So it get's some point's for being reliable which is important.

I never noticed any issues when hard switching off/on any antminer. All series boots up perfectly.

IIRC S2 had *some* issues with that though, due almost entirely to the beaglebone SD card (same reason for almost every BBB/Rpi+SD-based miners failing after power cycle)

[klondike_bar]

Did someone made some OC on the batch 8?

Ive tried to go as high as 712MHz successfully with errors rate of ~0.015% and temps of 55-65.  Didn't go any further because i dont have a kill-a-watt and am only using a single 1350W (enermax gold) PSU.

I suspect bitmain instilled the higher voltage in order to maximize hashrate/chip for short-term ROI. I suspect a B8 unit could exceed 800MHz/1420wDC/~1500wAC

a higher voltage means less amps drawn for the same wattage. so whatever overclocks a lower-voltage chip can achieve should be possible to exceed with a higher voltage in the B8

[notlist3d]

Did someone made some OC on the batch 8?

Ive tried to go as high as 712MHz successfully with errors rate of ~0.015% and temps of 55-65.  Didn't go any further because i dont have a kill-a-watt and am only using a single 1350W (enermax gold) PSU.

I suspect bitmain instilled the higher voltage in order to maximize hashrate/chip for short-term ROI. I suspect a B8 unit could exceed 800MHz/1420wDC/~1500wAC

a higher voltage means less amps drawn for the same wattage. so whatever overclocks a lower-voltage chip can achieve should be possible to exceed with a higher voltage in the B8

I don't think anyone has pushed it hard.  At 700 MHz on default it just is set pretty high already compared to other batches.

I don't see people pushing them past that to much.    Risk/reward just is not there especially with losing warranty if caught doing it.

[RadekG]

Bitmain's official response would support your idea of factory set fixed voltage:

Got the official response back on efficiency:  "Currently, S7 is fixed with frequency to make sure the hash rate is more stable. but the voltage can be adjusted. The power consumption is 0.25 J/GH + 10% as marked in website."

So it appears the 4.7 is constant.  And that efficiency is the +10 marked in specs.

It's been a bit since they sent that to me.  But it did mention fixed frequency.

I think this is chinese - english translation error. Bitmain's reply is explaining that INPUT voltage can be variable (adjusted), while frequency remain fixed and miner should work.

[RadekG]

Did someone made some OC on the batch 8?

I have two B8 OCed at 750MHz hasing at 5THs and 5.03THs. The garage is very hot (total about 15kW) and miners are running at 70/71C.

[yslyung]

Did someone made some OC on the batch 8?

I have two B8 OCed at 750MHz hasing at 5THs and 5.03THs. The garage is very hot (total about 15kW) and miners are running at 70/71C.

HW errors must be high

[charles2k]

and power consumption from the wall? (and what type PSU?)

Did someone made some OC on the batch 8?

I have two B8 OCed at 750MHz hasing at 5THs and 5.03THs. The garage is very hot (total about 15kW) and miners are running at 70/71C.

[RadekG]

Did someone made some OC on the batch 8?

I have two B8 OCed at 750MHz hasing at 5THs and 5.03THs. The garage is very hot (total about 15kW) and miners are running at 70/71C.

HW errors must be high

0.0078%/0.0186% only

[RadekG]

There is a PIC Microcontroller and a Digital pot controlling the Fb ground resistor. What is unknown at the moment is if this arrangement is tied into the main Controller in any way or if it is stand alone and either factory pre-set (most likely) or monitoring some parameter and adjusting accordingly?

I do not own a Batch 8 S7 so can run no checks, most likely that will be done by J4bberwock in the New year?

Rich

So, B8 has no PIC controller. Voltage is set at 10.5V. I don't think it will be SW controlled.

[RichBC]

So, B8 has no PIC controller. Voltage is set at 10.5V. I don't think it will be SW controlled.

The pictures show a PIC and a Digital Pot on the Batch 8 Boards. What is unknown at the moment is if it is stand alone /Factory Pre-set or if it is controlled by the main controller?

Rich