Tuning antminer S9i/j/ lower power consumption. braiinsOS

[0xdjangox0]

Hi all members.
How we can tune antminer for lower power consumption?
what is the relationship between voltage for chains and their performance and their power consumption.

I have 2 miners . both of them are on Braiins OS. I have full control over their frequencies and voltages.
I'm working on it for better performance and lower power consumption.
the default configuration for antminer s9 14.5TH on  braiin os is 8.8 V and frequency is 650Mhz.   i get 14.5TH on 8.6V and 675MHz and 1330W/h.
when i decreased the voltage to 8.4V . i get 14.5TH and 675MHz and 1252W/h.   it means power consumption decreased by 6%.

Do you have any experience with voltage modifications?
If i run on lower voltages what are the risks?

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[Artemis3]

There are no risks of running at lower voltages. Eventually you will simply get no hashing.

Your aim is to match ideal actual hashrates, if you see the actual is low, you need to increase voltage OR lower the speed. Try not doing both at the same time. This has to be done gradually, it takes a lot of time, and every hashboard reacts differently.

I think the best efficiency with the S9 is around 80W per TH. The existence of bOS forced Bitmain to release a firmware that allows some limited tinkering, but with bOS you can achieve a better result, it only takes more time and dedication.

There have been people here doing 500mhz at 8v, or 475mhz at 7.8v. You may also get good efficiency at higher speeds but you will have to measure power consumption a lot. Apparently the S9j has the best yields to tinker with.

You may find better efficiencies at lower overall rate, such as 10TH/s. This means 3 such miners would consume less electricity than 2 running at 15TH/s, while both produce the same 30 TH/s. Of course the slower ones run colder and quieter...

[0xdjangox0]

My 14.5TH s9i  by default running on 14.5TH and consume 1330W/h   at default frequency => 675Mhz and 8.6V
I  get  14.5TH    by changing voltage to 8.3  with power consumption 1230W/h   at default frequency => 675Mhz
It means that i save 9% of energy on 8.3 volt.  at lower voltage the hashboards needs more time to achieve their hashrates.

[BitMaxz]

Why not monitor this first for a day and let's see if there are spikes in hashrate to the pool and check how many rejected share you get on the miner's status. 
If you are getting some spikes and more rejected shares it means that your miner has unstable hashrate because of less power. So increase voltage value until you find a good sweet spot.

Sample data:

1st day
voltage: 8.3v
Hashrate: 14.5th
Rejected shares: 1000
Reported hashrate on the pool: 5 spikes

2nd day
voltage: 8.4v
Hashrate: 14.5th
Rejected shares: 800
Reported hashrate on the pool: 3 spikes.

Do this as your record daily and let's see if what voltage is more efficient.

[Artemis3]

My 14.5TH s9i  by default running on 14.5TH and consume 1330W/h   at default frequency => 675Mhz and 8.6V
I  get  14.5TH    by changing voltage to 8.3  with power consumption 1230W/h   at default frequency => 675Mhz
It means that i save 9% of energy on 8.3 volt.  at lower voltage the hashboards needs more time to achieve their hashrates .

Actually it is good if they manage to achieve their ideal hashrates after a while. You shouldn't rush it. And remember to treat each hashboard differently, you will find some can take voltages that others can't. They are not identical.

[0xdjangox0]

My 14.5TH s9i working fine with 8.3V on all chips.

My 14TH s9i working fine with 8.3V(1)/8.4V(2)/8.7V(3). on my 14TH i overclocked it to 14.5TH . my rejected shares are 0.196%. it is good.
both of my antminer's power consumption are 1224W/h.

i saved 200W/h for both of them with lower voltge.