The Bitmain Antminer S9i is an incremental improvement over the legendary Antminer S9, refining the same BM1387 chip platform with better power delivery and reduced noise. Released in 2018, the S9i delivered 14 TH/s at approximately 1,320W — a modest but meaningful efficiency gain over its predecessor. More importantly, Bitmain redesigned the cooling system, dropping noise levels from the S9’s punishing 85 dB down to a more manageable 76 dB.
The S9i represented Bitmain’s strategy of iterating on proven hardware rather than waiting for the next chip generation. For miners who had already invested in S9 infrastructure (PSUs, shelving, ventilation), the S9i was a drop-in upgrade that ran cooler, quieter, and slightly more efficiently. The improvements were not revolutionary, but for large-scale operations running hundreds of units, every percentage point of efficiency mattered.
In 2026, the S9i shares the same fate as the rest of the S9 family — no longer profitable for pure mining at standard electricity rates, but excellent as a Bitcoin space heater, a learning tool, and a piece of Bitcoin mining history. Its reduced noise level compared to the original S9 makes it slightly more suitable for home environments, and it remains fully supported by D-Central’s repair and conversion services.
Antminer S9i Full Specifications
| Specification | Details |
|---|---|
| Manufacturer | Bitmain |
| Model | Antminer S9i |
| Release Date | 2018 |
| Algorithm | SHA-256 |
| Hashrate | 14 TH/s (±5%) |
| Power Consumption | 1,320W (±5%) |
| Efficiency | 94.3 J/TH |
| Input Voltage | 11.6–13.0V DC |
| Dimensions | 350 × 135 × 158 mm |
| Weight | 4.2 kg |
| Noise Level | ~76 dB |
| Operating Temperature | 0–40°C |
| Cooling | 2 × 12038 fans |
| Network Connection | Ethernet (RJ45) |
| ASIC Chip | BM1387 (16nm) |
| Chips per Hashboard | 63 |
| Number of Hashboards | 3 |
| Total Chip Count | 189 |
| Power Connectors | 10 × 6-pin PCIe |
| Power Supply | APW3++ (sold separately) |
Performance Analysis
At 94.3 J/TH, the S9i is approximately 2% more efficient than the original S9 (96.4 J/TH) and comparable to the S9j (93.1 J/TH). Compared to modern hardware like the Antminer S21 (17.5 J/TH), the S9i uses roughly 5.4 times more energy per terahash. Within the S9 family, the efficiency gains are incremental rather than transformative.
The real improvement of the S9i over the original S9 is the noise reduction — dropping from 85 dB to 76 dB represents a meaningful decrease in perceived loudness. This made the S9i noticeably more tolerable for home mining setups.
Daily and Monthly Power Costs
| Electricity Rate | Daily Power Cost | Monthly Power Cost | Viability |
|---|---|---|---|
| $0.05/kWh | $1.58 | $48 | Viable only with near-free hardware — best as a space heater that earns sats |
| $0.08/kWh | $2.53 | $76 | Not profitable for pure mining — excellent as a dual-purpose heater |
| $0.10/kWh | $3.17 | $95 | Unprofitable — only makes sense if heat output offsets your heating bill |
| $0.12/kWh | $3.80 | $114 | Unprofitable — consider upgrading to a newer generation miner |
Heat Output
The S9i produces approximately 4,504 BTU/h of heat (1,320W × 3.412 BTU/W). Like all S9-family miners, this positions it perfectly for Bitcoin space heater conversions. The lower noise level compared to the original S9 makes the S9i a slightly better candidate for in-home heating setups.
Best Use Cases in 2026
Bitcoin Space Heater: The S9i is an excellent candidate for space heater conversion. Its lower noise profile (76 dB vs the original S9’s 85 dB) makes it more practical for home environments. D-Central offers Bitcoin Space Heater conversions that further reduce noise and optimize airflow for residential heating.
Learning and Education: Like the original S9, the S9i is perfect for new miners learning the ropes. The S9 platform has the largest body of documentation, tutorials, and community support of any ASIC miner ever made.
Solo Mining Lottery: Running an S9i on a solo mining pool is the Bitcoin equivalent of a lottery ticket that never expires. The odds are vanishingly small, but the cost is just your electricity bill.
Parts Donor: S9i components are interchangeable with the S9 and S9j, making broken units valuable for parts.
Common Issues & Repair
The S9i shares its failure modes with the broader S9 family:
- ASIC chip degradation: BM1387 chips can fail over time, especially in units that have run for years in high-temperature environments. Symptoms include reduced hashrate on one or more chains.
- Fan bearing wear: After years of 24/7 operation, fan bearings degrade. Noisy or slow fans should be replaced to prevent overheating.
- Connector corrosion: The 6-pin PCIe power connectors can develop corrosion or loose connections, causing intermittent power delivery issues.
- Control board failures: Ethernet port damage and firmware corruption are common after power surges or improper shutdowns.
D-Central offers professional Antminer S9 Repair services covering the entire S9 family (S9, S9i, S9j). See our ASIC Repair Cost Estimator for pricing.
D-Central Services for the Antminer S9i
- Repair: Full hashboard, control board, and fan repair — Antminer S9 Repair
- Space Heater Conversion: Quiet, effective home heating — Bitcoin Space Heaters
- Replacement Parts: Fans, control boards, connectors — Shop Parts
- Repair Cost Estimate: ASIC Repair Cost Estimator
Frequently Asked Questions
Is the Antminer S9i still profitable in 2026?
No, the S9i is not profitable for pure mining at standard electricity rates. At 94.3 J/TH, electricity costs far exceed mining revenue. However, as a dual-purpose space heater, the S9i effectively converts your heating bill into Bitcoin. If you are already paying for electric heat, the S9i lets you earn sats as a byproduct.
How much electricity does the Antminer S9i use per day?
The S9i consumes approximately 1,320W continuously, translating to 31.7 kWh per day or about 950 kWh per month. At $0.10/kWh, that is $3.17/day or $95/month in electricity costs.
Can the Antminer S9i be used as a space heater?
Yes. The S9i outputs approximately 4,504 BTU/h of heat and runs quieter than the original S9 (76 dB vs 85 dB), making it a solid candidate for space heater conversion.
What is the difference between the S9i and S9j?
The S9j offers a slightly higher hashrate (14.5 TH/s vs 14 TH/s) at similar power consumption (~1,350W), giving it marginally better efficiency. Both models have the same 76 dB noise level and share the same BM1387 chip platform. The differences are minor — choose whichever is available at a better price on the secondary market.