Product Overview

The Bitmain Antminer S21+ 235Th is a high-performance variant in Bitmain’s S21+ series — a flagship-class Bitcoin (BTC) SHA-256 ASIC miner delivering 235 terahashes per second at approximately 16.5 J/TH efficiency. The S21+ designation marks it as a premium step up from the standard S21 series, incorporating improved chip binning and efficiency optimisation within Bitmain’s 5nm platform.

The S21+ series bridges the gap between the cost-effective S21 standard models and the ultra-premium S21 Pro 245Th. With 235 TH/s and 16.5 J/TH, it delivers near-Pro efficiency at a hashrate level that makes it competitive with the best air-cooled Bitcoin miners currently available. The S21+ range is designed to give operators who want S21-generation performance a premium-tier option without stepping up to the highest-priced Pro variant.

For South African commercial Bitcoin mining operations, the S21+ 235Th offers an excellent combination of high hashrate density, state-of-the-art efficiency, and Bitmain’s established support and firmware ecosystem — making it a strong consideration for operators refreshing or expanding their fleets.

Key Features

• 235 TH/s hashrate: High-output Bitcoin mining in the premium S21+ series, delivering near-flagship performance per deployed rack unit.
• ~16.5 J/TH efficiency: At approximately 3875W, the S21+ 235Th operates at ~16.5 J/TH — a significant improvement over S19-era hardware (23–29 J/TH) and competitive with the best currently available air-cooled Bitcoin miners.
• Air-cooled design: Standard industrial ASIC enclosure with dual high-speed fans. No specialist hydro or immersion cooling infrastructure required for deployment.
• SHA-256d algorithm: Mines Bitcoin (BTC) as the primary target, with compatibility for Bitcoin Cash (BCH) and Bitcoin SV (BSV).
• Premium S21+ chip binning: The “+” designation indicates higher-tier chip selection from Bitmain’s 5nm manufacturing process, resulting in improved efficiency over standard S21-class hardware.
• Ethernet (RJ-45) connectivity: Single wired port for pool communication. Standard Antminer web interface for setup, monitoring, and firmware management.
• Bitmain flagship ecosystem: Full Bitmain support infrastructure including firmware updates, pool management, and compatibility with third-party mining management software.

Technical Specifications

• Algorithm: SHA-256d
• Supported coins: Bitcoin (BTC), Bitcoin Cash (BCH), Bitcoin SV (BSV)
• Hashrate: 235 TH/s (±3%)
• Power consumption: ~3875W (±5%) at 25°C ambient
• Power efficiency: ~16.5 J/TH (±5%)
• Cooling type: Air-cooled, dual high-speed fans
• Noise level: ~75 dB(A)
• Input voltage: 200–240V AC
• Networking: Ethernet (RJ-45)
• Operating temperature: 5°C to 40°C
• Dimensions (L×W×H): 400 × 195 × 290 mm
• Net weight: ~16 kg

Power & Installation Notes

South Africa’s 230V/50Hz supply is within the Antminer S21+ 235Th’s 200–240V input range. No voltage converter is required.

At approximately 3875W, the S21+ 235Th draws close to the maximum safe continuous load of a 32A circuit (32A × 230V = 7360W; at 80% safe load = 5888W — comfortable for one unit, with margin for a second). For single-unit installation, a dedicated 20A or 32A circuit installed by a registered electrician is required. For multi-unit farms, individual breakers per unit on a dedicated distribution board are essential.

Load shedding at ~3.9 kW means a 10kWh residential battery provides approximately 2.6 hours of operation at full load — insufficient for extended outages. Generator or commercial backup power is required for continuous operation. Plan for load shedding impact on effective daily operating hours.

Thermal management: the S21+ 235Th generates substantial heat and requires clear airflow at both inlet and exhaust fan faces, active air extraction from enclosed mining spaces, and ambient temperature maintained below 40°C. Active cooling may be needed in South Africa’s hot summer conditions in enclosed mining rooms.

Electricity Cost Context — South Africa

Running the S21+ 235Th at 3875W continuously consumes approximately 93 kWh per day, or roughly 2 790 kWh per month. At R2.80/kWh (reference residential tariff — municipal rates vary), the estimated monthly electricity cost is approximately R7 812 per month.

Calculation: (3875 ÷ 1000) × 24 × 30 × R2.80 = ~R7 812/month.

The S21+ 235Th’s 16.5 J/TH efficiency means it produces more Bitcoin per rand of electricity than older S19 or T21 hardware at the same power cost. Commercial or industrial electricity tariffs are strongly preferred for this class of machine. This is a cost estimate only — not a profitability projection.

Ideal Use Cases

• Premium commercial Bitcoin mining fleets: Commercial operations targeting state-of-the-art efficiency and high hashrate density in purpose-built mining facilities.
• Operators between S21 standard and S21 Pro 245Th: The S21+ 235Th sits in a premium mid-tier position — more efficient than the standard S21 series but at a lower cost than the flagship S21 Pro 245Th. See: Bitmain Antminer S21 Pro 245Th.
• Fleet refresh from S19k Pro or T21 hardware: A meaningful efficiency improvement step for operations currently running S19k Pro (23 J/TH) or T21 (20 J/TH) hardware.
• High-density rack deployments: At 235 TH/s per unit, operators maximise Bitcoin output per rack slot in space-constrained facilities.
• Pool mining at commercial scale: Compatible with all major SHA-256 Bitcoin pools. Reliable and predictable pool income from a proven Bitmain platform.

Frequently Asked Questions

Does the Antminer S21+ 235Th work on South African power?
Yes. SA’s 230V/50Hz is within the input range. A dedicated 32A circuit from a registered electrician is required for single-unit operation.

What is the difference between the S21+, S21 Pro, and S21 XP?
The S21+ 235Th runs at ~16.5 J/TH. The S21 Pro 245Th achieves ~15.5 J/TH (better efficiency, more hashrate, higher cost). The S21 XP Hydro 473T runs at ~13 J/TH but requires hydro cooling. The S21+ is a premium air-cooled option between the standard and Pro/XP tiers.

What Bitcoin pools are compatible with the S21+ 235Th?
Foundry USA Pool, AntPool, F2Pool, ViaBTC, Braiins Pool — all major SHA-256 Stratum-protocol pools. Configuration via the Antminer web interface.

Is there an S21+ 225Th as well?
Yes — the S21+ range includes a 225Th lower-hashrate variant at a more accessible unit cost. See: Bitmain Antminer S21+ 225Th.

How does load shedding affect the S21+ 235Th’s economics?
Each stage of load shedding reduces effective daily mining hours. At Stage 6 (~8 hours/day shedding), effective uptime drops to approximately 67% — significantly impacting daily BTC output. A backup power solution is essential for maximising ROI on premium hardware.

What’s Included

• 1× Bitmain Antminer S21+ 235Th ASIC miner unit
• Integrated PSU (confirm with order)
• Power cable (region-specific — South African plug may require local adaptor or electrician wiring)
• Ethernet cable not included
• Quick-start guide