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In-Depth Review of the Antminer S21: Bitmain's Most Efficient Bitcoin Mining Rig

In-Depth Review of the Antminer S21: Bitmain's Most Efficient Bitcoin Mining Rig

Jan 5, 2024

In-Depth Review of the Antminer S21: Bitmain's Most Efficient Bitcoin Mining Rig

The Antminer S21 is the latest model ASIC from Bitmain in the world of bitcoin mining. In this detailed analysis, we will delve into the specifications, design, and features of Bitmain's most advanced and efficient bitcoin mining rig to date. Released at the World Digital Mining Summit in September 2023, the Antminer S21 has set new standards for mining hardware, offering unparalleled performance. This article is based on a video review produced by Luxor.

Exterior Design:

Starting with the exterior, the Antminer S21 maintains a similar footprint to its predecessors but comes with a marginally increased weight. Weighing in at 15.4 kg, it is 1 kg heavier than the S19 XP and 2.2 kg heavier than the S19 J Pro. This robust construction hints at the premium components housed within the unit.

Power Supply Unit (PSU):

A notable feature of the S21 is its new power supply unit, the APW12-171215A, which is equipped with five high-voltage 500-volt capacitors. This PSU is designed to operate within a voltage range of 220 to 277 volts, showcasing its versatility. The use of a P14 (PA-45) plug type sets it apart from the S19 series, necessitating the need for a P13 cord and a specialized Power Distribution Unit (PDU) or a custom C20 to P13 cord for compatibility with the common C19 PDUs used in S19 setups.

Cooling System:

To tackle the immense heat generated by such a powerful machine, the S21 comes with the most potent fans ever installed in a Bitcoin miner, drawing 6.4 amps each. These high-current fans are strategically placed at both the front and back to maximize airflow and prevent overheating, ensuring the rig operates at optimal temperatures.

Interior Components:

Internally, the S21 boasts an Amlogic A113D control board, sharing connectors with the S19K Pro. This board uses four Molex Micro-Fit style connectors to support the powerful front and rear fans, meaning that any replacement of control boards would require a corresponding update to the fans to maintain functionality.


The core of the S21's mining capability lies in its three hashboards, which utilize the BHB68603 board type. Each hashboard is equipped with 108 chips, striking an optimal balance between chip count and efficiency. In comparison to other models in the S19 series, the S21's chip layout is designed to deliver a higher hash rate without compromising on energy consumption.

Power Supply Unit (PSU) Upgrades:

The S21's PSU is a significant upgrade over previous models, featuring 500-volt capacitors compared to the S19 J Pro Plus's 450-volt capacitors. These enhancements ensure a reliable and stable power supply, which is particularly crucial when overclocking the rig for maximum performance.


To sum up, the Antminer S21 represents a leap forward in Bitcoin mining technology. With its advanced design, powerful cooling system, and energy-efficient hashboards, the S21 is poised to become the go-to choice for miners seeking the highest return on investment. Stay tuned for our next segment, where we will put the Antminer S21 to the test under various temperature conditions to assess its real-world performance.


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