Product Overview

The Bitmain Antminer S21 Pro 234Th is a high-efficiency SHA-256 Bitcoin (BTC) ASIC miner built on Bitmain’s 5nm chip architecture. Delivering 234 TH/s at 3,510W, the S21 Pro 234Th sits as the entry-level configuration in the S21 Pro range, with the 245Th model occupying the top position. It is designed for professional Bitcoin mining operations where efficiency and long-term hardware performance are the primary concerns.

The S21 Pro series uses Bitmain’s latest-generation 5nm process node to achieve a power efficiency of approximately 15 J/TH — among the best available for air-cooled SHA-256 miners at time of release. This efficiency improvement over the previous S19 Pro series makes the S21 Pro range attractive for operators looking to reduce their per-TH electricity cost while increasing absolute hashrate output.

For South African Bitcoin mining operators, the S21 Pro 234Th represents a meaningful upgrade path from S19-series hardware. Its 230V compatibility, standard Ethernet interface, and Bitmain’s established support infrastructure make it a practical choice for both new builds and fleet upgrades in the South African market.

Key Features

• 234 TH/s SHA-256 Hashrate (±3%): Substantial Bitcoin mining power in a single unit. At 234 TH/s, the S21 Pro 234Th contributes meaningfully to major pool operations and is designed for continuous 24/7 operation.
• Industry-Leading 15 J/TH Efficiency: Built on a 5nm chip process, the S21 Pro achieves approximately 15 J/TH power efficiency — significantly better than the S19 Pro series and competitive with the best air-cooled miners available. Lower J/TH means lower electricity cost per unit of hashrate.
• Air-Cooled Industrial Design: Dual high-speed axial fans in a front-to-back airflow configuration manage the thermal load of the hashing boards. Suitable for rack deployment in purpose-built mining facilities with active ventilation.
• 3,510W Power Consumption: High absolute power draw requiring dedicated electrical infrastructure. Efficient per unit of hashrate, but the overall wattage demands proper circuit planning and PSU selection.
• Operating Noise ≤75 dB: Quieter than many comparable high-performance miners, the S21 Pro operates at industrial noise levels — not suitable for residential environments but manageable in purpose-built mining rooms.
• Compact and Rack-Compatible: The S21 Pro chassis is designed for standard mining rack deployment, maintaining compatibility with existing S19-generation rack infrastructure in many facilities.
• Ethernet Connectivity and Web Management: Standard RJ45 Ethernet port with a web-based management interface for pool configuration, monitoring, and firmware updates. Compatible with major ASIC management platforms.

Technical Specifications

• Algorithm: SHA-256
• Supported Coins: Bitcoin (BTC), Bitcoin Cash (BCH), and other SHA-256 cryptocurrencies
• Hashrate: 234 TH/s (±3%)
• Power Consumption: 3,510W (±5%)
• Power Efficiency: ~15 J/TH
• Cooling: Air-cooled, dual high-speed fans
• Noise Level: ≤75 dB
• Input Voltage: 200–240V AC, 50/60 Hz
• Networking: 1× RJ45 Ethernet
• Operating Temperature: 0°C to 40°C
• Humidity: 5%–95% (non-condensing)
• Dimensions (L×W×H): 400 mm × 195.5 mm × 290 mm
• Net Weight: ~15 kg
• Power Supply: Included (Bitmain APW12 or equivalent)

Power & Installation Notes

The Antminer S21 Pro 234Th draws 3,510W continuously, placing it in the high-wattage category. South African installations must comply with SANS 10142, and any new or modified electrical circuits must be certified by a registered electrician.

A dedicated 32A single-phase circuit is required as a minimum. Specify minimum 6 mm² cable for runs up to 10 metres; longer runs require uprated cable sized by your electrician. South Africa’s 230V / 50Hz supply is within the S21 Pro’s 200–240V input range — no transformer is needed. Confirm that your PSU is rated for 230V input.

Load shedding presents a practical challenge for S21 Pro operators. At 3,510W, a UPS or inverter large enough to sustain this unit through load shedding would require a minimum 5 kVA inverter with a substantial battery bank — typically 10 kWh or more for just two hours of runtime. This is beyond most residential solar/inverter systems. Operators should plan for load-shedding downtime or invest in commercial generator backup for uninterrupted operation.

Ventilation is critical for sustained performance. The S21 Pro exhausts significant heat from its rear fans. Deploy with directional extraction — inline duct fans or wall-mounted extraction units positioned to pull exhaust air out of the room. Keep ambient temperatures below 40°C to maintain rated hashrate and prevent thermal throttling.

Electricity Cost Context — South Africa

At Eskom’s approximate residential reference tariff of R2.80/kWh, the monthly operating electricity cost for the Antminer S21 Pro 234Th is estimated as follows:

(3,510 ÷ 1,000) × 24 × 30 × 2.80 = R7,076.16 per month

This is an operating cost estimate only — not a profitability projection. Actual electricity costs vary by municipality, tariff class, and supply arrangement. Many metropolitan areas in South Africa charge above R2.80/kWh for residential consumers. Commercial and industrial accounts may have different rate structures. Always verify your specific tariff before modelling Bitcoin mining economics.

At approximately R7,076/month in electricity, the S21 Pro 234Th is most viable for operators with access to commercial tariffs, renewable energy, or industrial power arrangements where per-kWh costs are substantially lower than residential rates.

Ideal Use Cases

• Professional Bitcoin mining farms: The S21 Pro 234Th is built for operators running multiple units in racked, ventilated mining facilities with industrial power supply and full network monitoring infrastructure.
• Fleet upgrades from S19 Pro or S19k Pro series: Operators retiring older Bitmain SHA-256 hardware will find the S21 Pro offers substantially better J/TH efficiency, reducing per-TH electricity cost and improving overall margin at the same hashrate tier.
• New Bitcoin mining builds: For South African operators setting up new SHA-256 mining infrastructure in 2024/2025, the S21 Pro 234Th represents a solid foundation — proven hardware from an established manufacturer with 5nm efficiency gains.
• Mixed-algorithm operations: Mining farms that also run Litecoin (LTC) and Dogecoin (DOGE) Scrypt miners can pair S21 Pro units in their SHA-256 rack rows for diversified coin exposure from a single facility.

Frequently Asked Questions

Does the Antminer S21 Pro 234Th work on South African power?
Yes. South Africa’s 230V / 50Hz grid supply is within the S21 Pro’s 200–240V / 50–60Hz input range. A dedicated 32A circuit and suitable PSU are required. Installation by a registered electrician is recommended for circuits of this scale.

What is the difference between the S21 Pro 234Th and the S21 Pro 245Th?
The S21 Pro 245Th offers 11 TH/s more hashrate than the 234Th variant, with a slightly higher power draw. Both share the same 5nm chip architecture and similar efficiency profiles. Choose the 234Th if price is a primary factor, or the 245Th if maximising absolute per-unit hashrate is the goal.

What mining pool should I use with the S21 Pro 234Th?
Major SHA-256 Bitcoin mining pools include Foundry USA, AntPool, ViaBTC, F2Pool, and Binance Pool. Access the miner’s web interface via its IP address on your local network, enter the pool’s stratum URL, and configure your worker name and password to begin mining.

How does the S21 Pro compare to the S19 Pro series in efficiency?
The S21 Pro achieves approximately 15 J/TH, compared to 29.5 J/TH for the S19 Pro 110T. This represents roughly a 50% improvement in power efficiency — a significant reduction in electricity cost per unit of hashrate for operators upgrading from S19-generation hardware.

Can the S21 Pro be run on a home inverter during load shedding?
Not practically. At 3,510W, the S21 Pro requires a large commercial inverter and substantial battery bank. Plan for downtime during load shedding unless you have dedicated generator or large-scale inverter capacity specifically sized for mining operations.

What’s Included

• 1× Bitmain Antminer S21 Pro 234Th mining unit
• Power supply unit (confirm at time of purchase whether PSU is included)
• Power cables
• Quick-start documentation