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Machine review · Oct 1, 2026 · 6 min read
Bitdeer SealMiner A3 Pro Hyd review: a good machine at a middling price
Bitdeer's best water-cooled machine makes a coin for about the same electricity as an S21-class Antminer, at a higher price per terahash than the machine next to it on our floor. Whether that is worth paying depends on one thing: what you are comparing it with.
Bitdeer SealMiner A3 Pro Hyd (666 TH/s)
The bottom line
The SealMiner A3 Pro Hyd is Bitdeer's best water-cooled machine: 660 TH/s from 8,250 W, 12.5 J/TH, launched in September 2025 as the top of the company's third-generation SEALMINER range. At our UAE site it makes a bitcoin for about $40,600 of electricity and returns roughly 38% in its first year at today's price.
Bought the week we first held a price for it, in April 2026, it has mined and kept 0.0583 BTC for $2,342 of power: $2,528 of cashflow against a $12,304 landed cost. That is 21% of the hardware in 183 days. Between now and the 2028 halving it has another 0.179 BTC in it, which with bitcoin back at its previous high is about 2.0× its hardware by the halving, still running afterwards.
What you are buying is a mature efficiency class at a price that has stayed put. What you are not buying is the cheapest coin on our floor, or the best first year: the S23 Hyd makes a coin for about $31,300 and the S23e Hyd 2U returns about 58% in year one.
Scores
| Criterion | Score | Why |
|---|---|---|
| Cashflow | 6.5/10 | Makes a bitcoin for about $40,600 of electricity at 6¢ and returns roughly 38% in year one at today's price. Solid, and below the 58% the S23e Hyd 2U returns. |
| Longevity | 7/10 | 12.5 J/TH is 300 kWh of power per petahash per day: $18.00 at 6¢ and $11.70 at 3.9¢, against a hashprice of $39.77 on 30 September. It stays above the line through the 2028 halving at both. |
| Efficiency | 6/10 | Good for last year and middling for this one: the S23 generation runs 9.5 to 10 J/TH on the same loop. |
| Quality control | 5/10 | Scored as unknown rather than as good. We found no operator reports of this machine's boards in the field, which is what a machine under a year old looks like. |
| Serviceability | 6/10 | Bitdeer's warranty runs 365 days from shipment, with the owner paying shipping to Bitdeer and Bitdeer paying it back. Hosted in the UAE, the Bitmain warranty centre is near the site but this is not a Bitmain machine, so repairs follow Bitdeer's route. |
Weighted on what an owner gets back per dollar over four years. It is efficient enough to clear the line comfortably at our sites, but it does not lead on cost per coin or on year one, and its reliability record is too young to score as good.
Buy it if
- You want a water-cooled machine that is not an Antminer, and you value Bitdeer's own firmware and silicon over the last few percent of return.
- Your power is at or below 6¢. At 6¢ it makes a coin for about $40,600; at 3.9¢, about $26,400.
- You are planning through the 2028 halving. At today's hashprice halved it still sits above the line at 6¢ and well above it at 3.9¢.
- You already have the loop, the three-phase supply and the racks, and you are buying in single-machine steps rather than a rack at a time.
Walk away if
- You are buying purely on first-year return. At $11.13 a terahash, the S23e Hyd 2U returns about 58% in year one against this machine's 38%.
- You want the cheapest coin. The S23 Hyd makes one for about $31,300 against this machine's $40,600, in the same room.
- You need a long public failure record. This machine has under a year in the field, and we score that as unknown rather than as good.
- Your power is well above 6¢. Up to about 6¢ it has room; between there and 8¢ it still clears today but leans on the price of bitcoin after the halving; above that, choose a more efficient machine.
What Bitdeer shipped
Bitdeer announced the A3 range on 17 September 2025 as the third generation of its in-house SEALMINER machines. Four models launched together: the A3 Pro Hydro at 660 TH/s and 12.5 J/TH, the A3 Pro Air at 290 TH/s and 12.5 J/TH, the A3 Hydro at 500 TH/s and 13.5 J/TH, and the A3 Air at 260 TH/s and 14 J/TH. The Pro Hydro is the top of the range.
Bitdeer's own listing gives it 660 TH/s from 8,250 W, with the launch announcement putting the power at 7,875 to 8,625 W. That is the tolerance on a 12.5 J/TH machine: 5% either side of the typical figure. The warranty is 365 days from shipment.
It is the water-cooled sibling of the air-cooled machine we reviewed earlier, the SealMiner A2 Pro Air, and it takes the same company's silicon from 14.9 J/TH there to 12.5 J/TH here. That is the step a water loop buys.
A price that has not moved since April
The first price we hold for it, on 2 April 2026, was $15.02 a terahash. Across the 127 days we have a price since, it has moved between $15.02 and $15.77. It is $15.23 today, $10,140 for the unit.
That is unusual. Most water-cooled machines we track settle after launch, and a flat line is the opposite of what a buyer hoping for a cheaper entry wants to see. It also tells you the market is not discounting this machine to clear stock: it is in stock and ships in days, at a price that has held for half a year.
Set against the water-cooled Antminers on our floor, the S23e Hyd 2U is $11.13 a terahash at 10 J/TH: cheaper than this machine and 2.5 J/TH more efficient. The S23 Hyd is $23.52 at 9.5 J/TH, and that extra price buys it the cheapest coin of the three. The entry price is the most important number in this review, and it is the one where this machine is weakest.
$15.23 a terahash today. The first price we held, in April, was $15.02.
What a coin costs it
At 6¢ in the UAE it makes a bitcoin for about $40,600 of electricity today. At Nigeria's 3.9¢ the same machine would make one for about $26,400, and it would cross there once, later in its life, when the trailing year says cheap power pays better. Water-cooled machines start in the UAE, where the loop, the 99% uptime and the warranty centre are.
The S23 Hyd, a generation ahead at 9.5 J/TH, makes one for about $31,300 in the same room. The S23e Hyd 2U, at 10 J/TH, makes one for about $32,400. A coin costs this machine roughly $40,600 against their $31,300 and $32,400: roughly a quarter to a third more electricity per coin.
That cost-per-coin gap does not decide the return by itself, because the machines cost different amounts. That is why the first-year figures differ the way they do. The S23e Hyd 2U returns about 58% in year one, the S23 Hyd about 31%, and the A3 Pro Hyd about 38%. It sits between them, and the S23e beats it on both counts. For the method behind these numbers, see the efficiency guide.
How it holds up through the halving
A machine's line is the hashprice at which it stops covering its own power. At 12.5 J/TH a petahash uses 300 kWh a day. That is $18.00 at 6¢ and $11.70 at 3.9¢.
Network hashprice was $39.77 per petahash per day on 30 September on our hashprice chart. The 2028 halving cuts the coins a petahash earns in half, at an unchanged price and difficulty, which would put it near $19.90. That is above the line at 6¢ by a little, and well above it at 3.9¢.
This is today's conditions held flat, not a forecast. What it says is that at 12.5 J/TH this machine is not at risk of being switched off at the halving at either rate, and that the extra 3 J/TH of the S23 generation buys distance beyond it, not survival. The guide to efficiency and halvings has the long version.
What is not known yet
The machine launched in September 2025, and April 2026 is the first price we hold for it. It has under a year in the field, and it is one of the least-written-about machines in its class. We looked for operator reports of its boards and found none we could stand behind, so there are none in this review. We score reliability as unknown, not as good.
What it costs you if something does fail is the part that matters. Bitdeer's warranty runs for 365 days from shipment. The owner pays to send a unit in and Bitdeer pays to send it back. Hosted with us, a fault is a repair queue, not a shipment from your own address, and it is a line item, not a catastrophe.
Our two cents
The A3 Pro Hyd is a good machine at a price that has not caught up with its competition. At 12.5 J/TH it clears its power with room at both our rates and carries to the halving. It is the right pick for someone who specifically wants Bitdeer, or who wants a water-cooled machine in stock today in single-unit steps.
For most buyers of water-cooled hashrate the better answer is nearby. The S23e Hyd 2U returns more in year one at a lower price per terahash, and the S23 Hyd makes the cheaper coin if you are buying for the years after the halving. If you have a room built for the 2U format, that is the one to look at first. Both are in the figure below, ranked on cost per coin and then year-one return.
- Bitmain Antminer S23 Hyd (563 TH/s) — 9.5 J/TH, In stock, $31,252 of electricity per bitcoin, 27% year one
- Bitmain Antminer S23 XP Hyd (600 TH/s) — 8.9 J/TH, Pre-order, $29,277 of electricity per bitcoin, 25% year one
- Bitmain Antminer S23e Hyd 2U (865 TH/s) — 10 J/TH, Pre-order, $32,441 of electricity per bitcoin, 51% year one
Sources and further reading
- Bitdeer launches 12.5 J/TH SEALMINER A3 — Yahoo Finance (Bitdeer release), 17 Sep 2025
- SEALMINER A3 Pro Hydro — Bitdeer, 2026
Which machines this covers
Disclosure
Firsthand Bitcoin sells and hosts mining hardware, including this machine. No manufacturer, distributor or affiliate programme paid for or reviewed this page and we take no commission on the links above. Historical figures are computed from daily bitcoin price and network hashprice, each day valued at its own prices. Nothing here is investment advice.