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Buying & marketPublished by Cipheron

New or used – how to spot a good used miner

With used miners, what counts is not the model name but what is inside – chip generation, hashboard version and substrate material. A checklist for the offer, the log and the unit.

A used miner costs less per terahash and has its early failures behind it. In return it is less efficient and usually comes without a manufacturer warranty. Whether that pays off depends on your electricity price: the more expensive the electricity, the more the new, more economical unit is worth it.

Chip generations at Bitmain

The model name does not tell you everything. What matters is the chip on the hashboards:

  • BM1398: S19, S19 Pro, T19, 29.5 to 37.5 J/TH depending on the model
  • BM1362: S19j Pro, S19j Pro+, 27.5 to 29.5 J/TH
  • BM1366: S19 XP, S19k Pro, 21.5 to 23 J/TH
  • BM1368: S21, T21, 17.5 to 19 J/TH
  • BM1370: S21 Pro, S21 XP, 13.5 to 15 J/TH

The newest generation needs at most about half as much power per terahash as the oldest.

Hashboard versions

The same model was often built with different hashboards. They differ in chip count, layout and board code and are not freely interchangeable. So ask for the board code and whether all three boards in the unit are the same version. On air-cooled Antminers of the S19 series and on the S21 the code starts with BHB, on the S21 Pro and S21 XP with A3HB, on hydro units with HHB or H6HB. Mixed boards point to a repair and make the next one harder.

Substrate material: FR-4, aluminium, copper

Hashboards come on different substrate materials:

  • FR-4 is the classic multilayer circuit board, used for example in the S19 Pro and in most S19 and S19j Pro units. Traces run through inner layers, and repairs are quite feasible.
  • Aluminium conducts heat better and is cheaper to manufacture. It is used for example in the S19 XP and in the S19a; the S19, S19j Pro and S19k Pro exist with and without an aluminium board. According to Bitmain, you can recognise the S19 with an aluminium board by its 88 instead of 76 chips per board. The drawback: the traces are on one side only, damage cannot be bypassed through inner layers, and repair requires higher soldering temperatures and preheating. If a fan fails, the whole board heats up.
  • Copper as a substrate is, in our experience, the better choice over aluminium. If a model comes in both versions, we take the copper version.

From below, you can recognise an aluminium board by its silver-grey metal surface. FR-4 is green, brown or blue.

Checklist for the offer

  1. Test report: hashrate per board over several hours, not just a photo of the dashboard.
  2. Chip count: The log must find the full chip count on every board.
  3. Hardware errors: A conspicuously high error rate on a single board signals a coming failure.
  4. Temperatures: The boards should run at similar temperatures. An outlier suggests poor thermal contact.
  5. Power supply: original model and matching power rating.
  6. Firmware: If the unit ran overclocked, it was stressed harder than the datasheet assumes.

Checklist at the unit

  • Dust and corrosion on heatsinks and connectors show how the previous owner cooled the unit. White or green deposits mean moisture.
  • Fans must start up smoothly, without a grinding noise.
  • Serial numbers on the chassis and the boards should match the offer.

When new is the better choice

At electricity prices where older chips leave hardly any margin, and whenever you need the manufacturer warranty. Used units in our shop are marked as such and come with a test report.

Sources

As of October 2026.

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