The Bitmain Antminer S9j represents the final evolution of the legendary S9 platform. Released in 2018 as the last major revision before the S17 generation, the S9j squeezed out 14.5 TH/s from the same BM1387 chip architecture — a 3.5% hashrate improvement over the original S9 and S9i at 14 TH/s. Bitmain achieved this through binning better-performing chips and optimizing voltage delivery, resulting in an efficiency of approximately 93.1 J/TH.
The S9j shares the same physical dimensions, fan configuration, and form factor as its predecessors, making it a direct drop-in replacement in existing S9 setups. Like the S9i before it, the S9j benefited from the improved cooling design that brought noise levels down to approximately 76 dB — a significant improvement over the original S9’s 85 dB. For operations running multiple units, the cumulative noise reduction was substantial.
In 2026, the S9j sits in the same position as the rest of the S9 family: retired from competitive mining but thriving as a Bitcoin space heater, an educational tool, and a solo mining lottery ticket. As the best-performing variant of the S9 platform, it offers the most favorable efficiency-to-cost ratio for anyone looking to repurpose S9-era hardware. D-Central Technologies provides full repair, parts, and space heater conversion services for all S9 variants.
Antminer S9j Full Specifications
| Specification | Details |
|---|---|
| Manufacturer | Bitmain |
| Model | Antminer S9j |
| Release Date | 2018 |
| Algorithm | SHA-256 |
| Hashrate | 14.5 TH/s (±5%) |
| Power Consumption | 1,350W (±5%) |
| Efficiency | 93.1 J/TH |
| Input Voltage | 11.6–13.2V DC |
| Dimensions | 350 × 135 × 158 mm |
| Weight | 4.2 kg |
| Noise Level | ~76 dB |
| Operating Temperature | 0–40°C |
| Humidity | 5–95% |
| Cooling | 2 × 12038 fans (6,000 RPM) |
| Network Connection | Ethernet (RJ45) |
| ASIC Chip | BM1387 (16nm) |
| Chips per Hashboard | 63 |
| Number of Hashboards | 3 |
| Total Chip Count | 189 |
| Power Supply | APW3++ (sold separately) |
Performance Analysis
At 93.1 J/TH, the S9j is the most efficient variant of the S9 family — approximately 3.4% better than the original S9 (96.4 J/TH) and roughly 1.3% better than the S9i (94.3 J/TH). These are incremental gains within the same chip generation. Compared to modern miners like the Antminer S19 (34.2 J/TH) or the Antminer S21 (17.5 J/TH), the S9j is multiple generations behind in efficiency.
The S9j’s 14.5 TH/s hashrate was impressive in 2018 but represents less than 0.01% of what a single S21 produces. The economics only work in 2026 when hardware acquisition cost is near zero and electricity is cheap or free.
Daily and Monthly Power Costs
| Electricity Rate | Daily Power Cost | Monthly Power Cost | Viability |
|---|---|---|---|
| $0.05/kWh | $1.62 | $49 | Viable as a space heater that earns sats — hardware cost near zero |
| $0.08/kWh | $2.59 | $78 | Not profitable for pure mining — excellent as a dual-purpose heater |
| $0.10/kWh | $3.24 | $97 | Unprofitable — only viable if offsetting heating costs |
| $0.12/kWh | $3.89 | $117 | Unprofitable — upgrade to a newer generation for pure mining |
Heat Output
The S9j produces approximately 4,606 BTU/h of heat (1,350W × 3.412 BTU/W). Combined with its lower noise profile compared to the original S9, the S9j is one of the best S9 variants for Bitcoin space heater conversion. See our Bitcoin Space Heater vs Electric Heater cost comparison.
Best Use Cases in 2026
Bitcoin Space Heater: As the best-performing S9 variant with reduced noise, the S9j is the ideal candidate for space heater conversion. D-Central offers Bitcoin Space Heater conversions that transform the S9j into a quiet home heating unit that mines Bitcoin as a byproduct.
Learning and Education: The entire S9 platform remains the most documented ASIC miner in history. The S9j is an excellent low-cost entry point for learning pool mining, firmware management, and basic repair.
Solo Mining Lottery: At 14.5 TH/s, solo mining a block is statistically improbable — but not impossible. Some Bitcoiners keep an S9j running 24/7 as a perpetual lottery ticket.
Parts and Resale: Working S9j units and their components retain value in the repair market.
Common Issues & Repair
The S9j shares failure modes with the entire S9 family:
- BM1387 chip failures: After years of continuous operation, individual ASIC chips can fail, reducing hashrate on affected chains. Chip-level repair can restore full performance.
- Fan degradation: The 12038 fans are the first components to wear out. Replace at the first sign of grinding noise or reduced airflow to protect the hashboards.
- Power connector issues: The 6-pin PCIe connectors can develop high-resistance connections over time, leading to intermittent shutdowns or reduced hashrate.
- Firmware corruption: Power surges and improper shutdowns can corrupt the control board firmware. Recovery via SD card is straightforward — see our SD Card Firmware Recovery Guide.
D-Central offers professional Antminer S9 Repair services covering all S9 variants. See our ASIC Repair Cost Estimator for pricing.
D-Central Services for the Antminer S9j
- Repair: Full hashboard, control board, and fan repair — Antminer S9 Repair
- Space Heater Conversion: Optimized for home heating — Bitcoin Space Heaters
- Replacement Parts: Fans, boards, connectors — Shop Parts
- Repair Cost Estimate: ASIC Repair Cost Estimator
Frequently Asked Questions
Is the Antminer S9j still profitable in 2026?
No, the S9j is not profitable for pure Bitcoin mining at standard electricity rates. At 93.1 J/TH, it consumes far more power per hash than modern miners. However, when used as a space heater, the economics change entirely — you are paying for heat regardless, and the S9j lets you earn sats while heating your space.
How much electricity does the Antminer S9j use per day?
The S9j consumes approximately 1,350W continuously, translating to 32.4 kWh per day or about 972 kWh per month. At $0.10/kWh, that is $3.24/day or $97/month in electricity costs.
Can the Antminer S9j be used as a space heater?
Absolutely. The S9j is one of the best S9 variants for space heater conversion due to its combination of slightly higher hashrate and lower noise. D-Central offers purpose-built space heater conversions for the S9j.
Which S9 variant should I buy in 2026?
If you are buying on the secondary market for space heater conversion, the S9j is the best option — highest hashrate (14.5 TH/s) with the lowest noise (76 dB). However, the differences between the S9, S9i, and S9j are small. Buy whichever is cheapest and in the best physical condition.
Is the S9j compatible with the APW3++ power supply?
Yes, the S9j uses the same APW3++ power supply as the S9 and S9i. Ensure your PSU is rated for at least 1,350W output and has the required 10 six-pin PCIe connectors.