By Jules Porter | October 10, 2026
Immersion cooling has its own efficiency leaderboard. Hydro miners often dominate the absolute low-J/TH charts, but they are not the same thing as immersion miners. In a true immersion system, the mining hardware is designed to run submerged in dielectric fluid while pumps, heat exchangers and external heat rejection move the heat away from the tank.
This ranking covers factory-built SHA-256 Bitcoin miners intended for immersion cooling. Converted air-cooled miners and hydro units are excluded. Machines are ranked by watts per terahash (W/TH). Numerically, W/TH is the same efficiency metric miners usually write as J/TH because one watt is one joule per second and hashrate is measured per second.
| Rank | Miner | Nominal hashrate | Miner power | Efficiency |
|---|---|---|---|---|
| 1 | Bitmain Antminer S23 Immersion | 442 TH/s | 5,304 W | 12.0 W/TH |
| 2 | Bitmain Antminer S21 XP Immersion | 300 TH/s | 4,050 W | 13.5 W/TH |
| 3 | MicroBT WhatsMiner M66S++ | up to 356 TH/s | about 5,518 W | 15.5 W/TH |
| 4 | Auradine Teraflux AI3680 | 250 TH/s normal mode | about 4,000 W implied | 16.0 W/TH |
| 5 | Bitmain Antminer S21 Immersion | 239 TH/s normal mode | 3,824 W | 16.0 W/TH |
1. Antminer S23 Immersion — 12.0 W/TH
Bitmain’s Antminer S23 Immersion is the clear efficiency leader in this factory-immersion list. Current model references place it at 442 TH/s and 5,304 W, which works out to exactly 12 W/TH. ASIC Miner Value currently identifies the machine as oil-immersion cooled, while multiple S23 references show the same 442 TH/s and 5,304 W nameplate combination.
The S23 Immersion does not beat Bitmain’s newest hydro hardware, but that is not the comparison here. Against purpose-built immersion miners, 12 W/TH is a major step forward. It is also significantly more efficient than the earlier liquid-cooled machines in our broader 2026 efficiency ranking.
2. Antminer S21 XP Immersion — 13.5 W/TH
The S21 XP Immersion remains an unusually strong machine even after the S23 arrived. Its published specification is 300 TH/s at 4,050 W, or 13.5 W/TH. That figure is also independently documented in CleanSpark’s 2024 SEC filing describing its purchase of 26,000 S21 XP Immersion servers.
The S21 XP Immersion is a useful reminder that immersion itself does not automatically create a lower W/TH number. The efficiency comes from the silicon, voltage-frequency operating point and thermal envelope. Immersion gives the miner a more controlled way to remove heat and enables dense, fanless deployment.
3. WhatsMiner M66S++ — 15.5 W/TH
MicroBT’s WhatsMiner M66S++ is the most efficient M66-series immersion model in this ranking. The current M6X documentation lists the M66S++ at 314–356 TH/s and 15.5 W/TH. At the top of that published range, 356 TH/s corresponds to roughly 5,518 W of miner power. MicroBT’s own immersion operation guide identifies the M66S++ as an immersion-cooling model.
This is also why the M66S++ belongs above the older M66S+ and M66S. The family steps down from roughly 15.5 W/TH for the M66S++ to 17 W/TH for the M66S+ and around 18.5–19.9 W/TH for earlier bins. The exact unit and firmware mode still matter.
4. Auradine Teraflux AI3680 — 16.0 W/TH in Normal Mode
Auradine’s Teraflux AI3680 is one of the more unusual miners on this list. Auradine’s own datasheet identifies its cooling mechanism as single-phase immersion and specifies a normal operating point of 250 TH/s at 16 W/TH. That implies roughly 4,000 W of ASIC power at the normal operating point. The same datasheet lists a faster turbo mode around 365 TH/s at 19 W/TH, so the faster setting is less efficient.
Some third-party databases advertise the AI3680 at 15 W/TH and 375 TH/s. For this ranking, BitcoinVersus.Tech uses the manufacturer’s own current datasheet instead of the more aggressive reseller figure. That keeps the comparison conservative and reproducible.
5. Antminer S21 Immersion — 16.0 W/TH
The standard Antminer S21 Immersion ties the AI3680 at 16 W/TH in its normal energy mode. Bitmain’s published manual lists a 239 TH/s bin at 3,824 W and 16 W/TH, alongside other normal-mode bins at the same efficiency. High-energy mode raises hashrate but also moves efficiency to about 18.5 W/TH, so that mode is not used for this ranking.
Why W/TH Is Only the Miner-Level Number
A 12 W/TH miner does not mean the entire immersion facility operates at 12 W/TH. Pumps, dry coolers, heat exchangers, coolant distribution, transformers and conductor losses all consume power. The same distinction applies to air and hydro systems. Our guide Your ASIC’s J/TH Is Not Your Site’s J/TH explains why nameplate miner efficiency and site efficiency are different measurements.
Immersion can still improve operations in ways that do not appear directly in the W/TH line: no miner fans, lower dust exposure, reduced thermal cycling, higher power density and better control of chip temperatures. But those benefits have to justify tanks, dielectric fluid, pumps, heat rejection and service procedures.
The 2026 Immersion Efficiency Frontier
The gap from the S21 Immersion’s 16 W/TH to the S23 Immersion’s 12 W/TH is a 25% reduction in miner energy per terahash. That is a meaningful generational change. It also shows why operators should compare the actual cooling architecture before using a generic “liquid cooled” label: hydro and immersion hardware have different pumps, plumbing, fluids, electrical requirements and service procedures.
For a broader comparison across manufacturers and cooling types, see our MicroBT versus Canaan air, hydro and immersion fleet comparison. For conventional fan-cooled hardware, we also ranked the five most efficient air-cooled Bitcoin miners.
Methodology: Factory-built SHA-256 miners explicitly designed for immersion cooling, ranked by the lowest manufacturer-supported normal/nameplate W/TH available in published documentation. Hydro miners, air miners converted for tanks and reseller-only overclock claims are excluded. Where third-party listings conflict with manufacturer documentation, the manufacturer value wins. Figures checked October 10, 2026.
Primary specification references: ASIC Miner Value S23 Immersion profile; CleanSpark SEC filing for S21 XP Immersion nameplate data; MicroBT immersion operation guide; M6X specification table; Auradine AI3680 datasheet; and the BITMAIN S21 Immersion manual mirror.
Editor’s Note: Machine-level W/TH can shift with inlet-fluid temperature, firmware, voltage, silicon variation and power mode. Confirm the exact delivered bin and site operating conditions before procurement.
BitcoinVersus.Tech independently researches Bitcoin mining hardware, semiconductor technology, data centers and computing infrastructure. Donations help fund additional open technical publishing: 3C9o19EH5HSiwEPyCTmEKzxhNCbo2X6TTb
BitcoinVersus.tech is not a financial advisor. Content is provided for informational purposes.
Leave a Reply