my epic controlled 2 board t21 with repasted heatsinks work really well.

The miner would run just fine without heatsinks, it will work for a few seconds then it will overheat and will give you a temp-error in the kernel log and goes to sleep or on some models it would just enter a reboot-loop, I think what you are describing is the chip itself is loose in respect to the PCB, and that my friend is most likely the reason.

@danieleither, I can tell you for a fact that in most cases, the bad boards will die during a power recycle, mainly caused by what's known as "thermal shock," the rapid change of temp will crack poor solder joints, the miner is more likely to break when it goes from hot to cold than staying hot, you already had at least one badly soldered chip, when you powered the miner off temp changed very rapidly from 70c or so to near room temp, what happened there is uneven shrinking of different components, the result is a mechanical stress on the chips to the PCB, so now there is a "short" in that hashboard and thus it's reading 0 asics whereby in reality it could be just 1 bad ship that needs resoldering, funny enough, this shit only happens on Antminers, it was very common on their 17 series in general and anything with a T is usually terribly made by Bitshit.

If you are still deep into mining and using Antshit, you may consider getting a fixture tool and some tools to start fixing your own hashboards, if you don't have shaky hands, I believe you are smart enough to figure it out.

What exact procedure of maintenance do you do? Did you just use compressed air to clean them up?

How about the temp and fan speed?

If it worked before, I believe this undetectable ASIC chips has poor contact with the heatsink.
If you can disassemble the unit again, I recommend cleaning it up, removing the old thermal paste, and replacing it.

Also, test them one by one because sometimes other hashboard affects the other hashboard to send false signals.

well three hashboards from good to bad with a controlled turn off is odd.

did you try swapping three white wires from controller to hashboard?

i am running four t21s but on six cases two boards per case and epic controllers.

i have had one bad epic controller that gave me false readings.

i used about 17 epic controllers.

and i get a dead board read on and off  with one t21 board.

So it is a definite maybe the controller or the wires and less likely the hashboards.

Well there is variance Maybe we did not drop -2% last jump

and maybe we did not gain the +5% this jump.


Also the s21xp really works efficiently. Many days my 2 do around 12.5 watts a th. So we could just be seeing companies switching out s21's for s21 xp's

a 17 or 18 watter for a 12.5 to 13.5 watter is a big improvement

200 th burning 3500 watts
270 th burning 3500 watts

70 th for free in terms of power cost.

70 x 5.5 cents is $3.85 a day more income for same power cost.

Yes, I am using the website's default preset. I don't know OP's electricity, and it's nowhere mentioned.
I did mention that the total profit will vary based on OP's electricity bill.

S21 Pro's without electricity bill profit is also mentioned (Depending on when the profit is estimated considering the bitcoin's at the moment value).

The average electricity bill in Europe is around 0.28 Eur. Asian countries have even lower, around 0.1$

Asicminervalue is showing an estimated profit of '$14.18' daily for Antminer S21 Pro.
The estimated cost of electricity per day's use is '$8.47' - Electricity cost isn't mentioned, so this value varies depending on your electricity cost.

The total estimated profit will be $5.71.

ASICs are expensive, and the stock gets sold more quickly than GPUs. At eBay, sellers usually sell used ASICs cheaply, but I wouldn't go that route.

I’m considering adding an S21 Pro to my home mining setup, but I’m hesitant due to the high electricity costs here in Ireland. I’m worried the earnings might just cover the electricity bill. My other option is to go for an S21e XP Hydro and host it instead. Any suggestions?

high power costs means you need the most efficient gear.

if you want to mine BTC you need this gear:

https://altairtech.io/product/bitmain-antminer-s21-xp/

it is costly about 7,600 usd a unit or 6,208 pounds

if you sink in 100k you get 15 pieces = 93,120 pounds with left over for wiring filters cooling.

15 units do 4,050 th or  187.52 pounds a day  no power cost figured in. So in 500 days if power was zero you would break even.

the real question is what do you burn .  15 units burn 1335 kwatts a day that is 133.50 pounds of you power cost is .10 pounds a kwatt

or 187.52-133.50 = 54.02 pounds a day profit.  1740 days to pay off the gear.

So 94,000 pounds for the best gear to mine btc will be terrible at .10 pounds a kwatt. higher cost would be worse

what does your power cost?

.10 pounds      54.02 pound daily profit
.11 pounds      40.67 pound daily profit
.12 pounds      27.32 pound daily profit
.13 pounds      13.97 pound daily profit
.14 pounds          .62 pound daily profit


So If I were you I would not do it at .10 pounds a kwatt or higher power cost.

Definitely I can recommend oneminers - https://oneminers.com/ .
98% uptime so far. 7 Years warranty for miners and free repair for miners within 7 years warranty.
Basically they offer miners and have advanced managed platform so you can manage it from phone. (the majority of the miners are supported).
Now they have promo for 7 days trial - Time limited. Basically it is not a lot but you have free electricity for first 7 days That is all.
The dashboard is quite comprehensive. Here is a sample:

They have hosting in Finland, Norway, Germany, USA, Dubai and newly Ethiopia.
The central they have in Texas - Austin and in Europe .
You can buy on their platform or also use their hosting and send miner there to manage it (it costs about 100$ per KW of the miner infrastructure fee) but you can super cheap electricity afterwards .

at danieleither

my four are fine.

but they use epic control boards and are set to 3000 watts.

They all use 240 volt psu's the one that the s19xp's use.

 these psu's just version f spec to 277 watts.




https://altairtech.io/product/apw121215-bitmain-power-supply-psu/

must be version f



and my units are doing about 17 watt a th

I have spare oem t21 high volt psu's and wires I could send them to you as I do not need them.

are you in usa? if I recall you are not in usa

Are you using the Bitmain PDU's? I've had a LOT of problems with my T21's, but most have been attributable to poor termination of cables to the rear of the PDU sockets. These sockets are TERRIBLE in design, often the pins come out on the rear of the PDU socket (therefore dropping a phase). The miners still power up but display all sorts of problems and error messages (not related to power) such as 0 Asics detected, messages about checking connections to hashboards etc