Antminer Real-world efficiency way off spec

[yj.Jang]

Hi everyone,

I am currently testing multiple Antminer S21 XP Hyd units to evaluate whether they are viable for a full container-scale deployment.

To start, I ordered 36 units to match the capacity of a small-scale hydro cooling setup. I have been running tests across these units using different firmware options: Stock firmware, VNish, and Braiins OS.

Surprisingly, in almost every scenario, the real-world efficiency rarely matches the manufacturer's official specifications.

Out of the entire batch, only 1 or 2 units running on the stock firmware manage to hit the advertised efficiency numbers. Furthermore, even for those select few units, achieving that spec efficiency is only possible when the ambient temperature remains strictly under 30°C.

I wanted to reach out and check with the community:

What are your experiences with the S21 XP Hyd?

Are other Antminer users actually seeing performance and efficiency that match the official spec sheets in your setups?

Looking forward to hearing your insights and results.

[FP91G]

What's not working for you? Are your results deviating from the manufacturer's hashrate and energy efficiency specifications?
(1-1) The hashrate value, and power efficiency on wall are all typical values. The actual hashrate value fluctuates by ±3%, and the actual power efficiency on wall fluctuate by ±5%.
https://shop.bitmain.com/product/detail?pid=00020250806183122100IOerDTTH068C

[crypto_curious]

Surprisingly, in almost every scenario, the real-world efficiency rarely matches the manufacturer's official specifications.

Out of the entire batch, only 1 or 2 units running on the stock firmware manage to hit the advertised efficiency numbers. Furthermore, even for those select few units, achieving that spec efficiency is only possible when the ambient temperature remains strictly under 30°C.

what were your results then? Off by how much?

[FP91G]

This ASIC has three operating modes with standard firmware:

Normal Mode: 473 TH/s and 5676 W.
High Performance / Plus Mode: 500–515 TH/s and 6100–6300 W.
Energy Saving / Low Power Mode: 380–410 TH/s and 4300–4600 W.

It also has an additional overheat protection mode called Dynamic Frequency Scaling. As the chip temperature increases, the operating frequency decreases, and the hashrate drops.
S21 XP Hyd Specification

[philipma1957]

bitmain has temperature sensitivity with air-cooled gear.

nice to see it is consistent with liquid cooled gear.

the chips are what do it. once they warm beyond 75C the efficiency drops.

my s21xps will do 3400 to 3700 watts depending on ambient air temps.

they are hosted in Iowa and in the winter under 40f they run way better then in the summer over 80f.

my guess on water cooled if the radiators can't eliminate heat as well when it is 30c or more.


How bad is it for you 10% off is common when warm

and -5% is common when cold with air cooled.

average it out and you are near 5% off for the year.

please post back as I would love to get some info on the liquid cooler gear. My host wants to begin with liquid cooled gear and I

am on the fence about getting a few s23xp hydros.