New or used ASIC miner? How to decide and what to check
A new ASIC miner pays off when you want the best efficiency, a full warranty and the longest possible earning life. A used miner makes sense when it is significantly cheaper, comes from a recent generation and you have cheap electricity. Otherwise its poorer efficiency eats up the savings on price. With a used machine, the key is that it has been tested and comes with a warranty.
Summary
- What matters is the price per 1 TH/s, efficiency in J/TH and your electricity price – not just the purchase price.
- An older generation has less headroom: after the 2028 halving it may become loss-making sooner.
- Always test a used machine: hashrate of each hashboard, chip count, temperatures, PSU.
- Buy with a receipt and a warranty. Never pay upfront for a machine nobody has seen running.
New and used miners in numbers
| Criterion | New miner | Used miner |
|---|---|---|
| Purchase price | higher | lower, depending on generation and condition |
| Efficiency | current generation, e.g. S21 Pro+ 15 J/TH, S23 Hyd 9.5 J/TH | often an older generation, e.g. S19 at around 34 J/TH |
| Warranty | 24 months with us | depends on the seller; usually none from a private individual |
| Hidden defects | minimal risk | worn fans, dried-out thermal paste, corrosion, faulty chips |
| Economic lifespan | longest | shorter, depending on generation |
| Resale value later | good | falls with every new generation |
How to work out which pays off more
Compare how much the machine earns after paying for electricity. Today, 1 TH/s on Bitcoin brings in roughly 0,84 Kč per day. Example for hosting at 1.13 CZK/kWh, as of 18 October 2026:
| Item | Older generation: Antminer S19k Pro 120 TH/s | Current generation: Antminer S21 Pro+ 245 TH/s |
|---|---|---|
| Efficiency | 23 J/TH | 15 J/TH |
| Electricity per 1 TH/s per day | 0.62 CZK | 0.41 CZK |
| Profit per 1 TH/s per day | 0.22 CZK | 0.43 CZK |
| Profit of the whole machine per day | 26 CZK | 106 CZK |
| After the halving (revenue 0.42 CZK/TH, otherwise unchanged) | −24 CZK per day | +3 CZK per day |
The more efficient machine earns twice as much per terahash and stays at break-even after the halving, while the older generation falls into a loss. The calculation is simplified – the exchange rate and difficulty will change in the meantime. A used older-generation machine should therefore be significantly cheaper per 1 TH/s so that it pays for itself before it stops earning. How quickly machines age is shown in the article ASIC miner lifespan; break-even electricity prices for other models are in the article ASIC power consumption and J/TH.
What to check on a used miner
- Live test: let the machine run for at least 30–60 minutes. The hashrate must be close to the manufacturer's figure.
- Hashboards: in the web interface, check that all boards are running and each reports the full chip count. The boards should have similar hashrates.
- Temperatures: with the same airflow, the boards must not differ much. One noticeably hotter board means work for a service centre.
- Fans: no bearing noise, similar speeds on all of them.
- PSU and cables: no restarts, connectors without discolouration or a burnt smell.
- Appearance: green or white deposits on the boards, rust on heatsinks and traces of liquid point to a humid environment.
- Firmware: find out whether it is stock or alternative – alternative firmware means a fee and may affect the warranty. More in the article Firmware and software for ASICs.
- Origin: serial number on the label, an invoice from the previous owner and any remaining manufacturer's warranty.
When buying used makes sense and when it does not
It makes sense when you have cheap electricity (for example in hosting), you are buying a recent-generation machine, you need a replacement for a faulty unit, or you want to start mining with a smaller investment and a shorter horizon.
It does not make sense when you will mine at home at a normal electricity price, when the generation is already on the edge of a loss today, or when the seller will not show the machine running. Beware of offers of “cheap machines on pre-order” – we explain how this scam works in the article Pre-orders for non-existent miners.
Common mistakes when choosing
| Mistake | Why it matters |
|---|---|
| Deciding on the machine price alone | A cheap machine with high J/TH can lose money on electricity. |
| Buying without a test | You only discover a faulty hashboard or PSU at home. |
| Not accounting for the halving | Revenue per 1 TH/s halves roughly every four years. |
| Forgetting about power and noise | A large miner needs a dedicated circuit and hums at around 75 dB. |
What next
In the Used category we offer checked used miners from our workshop with a warranty; new machines are in the ASIC miners category. You can calculate the payback of a specific option in the mining investment calculator.
Sources
Frequently asked questions
What warranty does a used ASIC miner come with?
Is a used Antminer S19 worth buying?
Is it safe to buy a miner from a classified ad?
What is better for a beginner?
This text was prepared with the help of AI. Facts, figures and procedures were checked by Yegor.
