Buying used ASIC miners: a due-diligence checklist

1. Start with the price per terahash

Compare offers in $/TH, not per unit. A 200 TH/s machine at $3,000 costs $15/TH; a 100 TH/s machine at $1,200 costs $12/TH but may burn twice the power per terahash. Check the efficiency (J/TH) at the same time: the price only makes sense against the band the machine belongs to.

The Segments Gulf ASIC Price Index publishes weekly medians per efficiency band, hosted and ex-works. An ask far below its band median is the first warning sign of a scam or a damaged unit, not a bargain.

2. Confirm the machine is what the ad says

1. Ask for photos of every serial sticker: the chassis label, the control board, each hashboard and the PSU. The model and hashrate printed on the chassis label must match the ad.
2. Ask the seller to film the label with a handwritten note showing today’s date and your name. Stock photos and recycled pictures fail this immediately.
3. Check the chassis serial with the manufacturer. Bitmain and MicroBT both offer warranty lookups by serial; the result shows the model, the production batch and whether warranty is still active.
4. Compare the hashboard serials and board codes with the model. Boards from a lower bin or another model fit the same chassis, so a swapped board is invisible from the outside.
5. Ask for a screenshot of the miner’s web interface and kernel log. Every chain should report the full chip count for the model; missing chips mean a repaired or failing board.

3. Test it on a pool you control

A dashboard screenshot proves nothing; a pool screenshot is easy to edit. Before you pay the balance, have the seller point the machine at your own pool account with a worker name you choose, and watch it for 24 to 48 hours.

• Pool-side accepted hashrate within 5% of nameplate, averaged over at least 24 hours.
• Reject rate under 1% and no hardware-error spikes in the miner log.
• Chip temperatures inside the manufacturer range and all fans reporting RPM.
• No reboots: check the uptime counter at the start and end of the test.
• If the machine runs custom firmware, ask whether it is tuned. A unit tuned above nameplate can look great for a day and degrade quickly.

4. Warranty and repair history

Manufacturer warranty follows the serial number, not the invoice holder, but some vendors refuse claims on machines that ran custom firmware or were opened by a third party. Ask for the original invoice, the warranty end date and any repair tickets.

Ask directly whether any hashboard has been replaced or reworked. A repaired machine is not a bad machine, but it should be priced as one and disclosed in the ad.

5. Agree DOA terms in writing

Dead-on-arrival terms decide who pays when a machine fails on delivery. Put them in the invoice or a short purchase agreement before you pay:

• The DOA window, typically 3 to 7 days from delivery or plug-in.
• What counts as DOA: no boot, a missing chain, hashrate below an agreed percentage of nameplate.
• The evidence required: an unboxing video, the kernel log and a pool test.
• The remedy and who pays return shipping: replacement, refund or a repair at the seller’s cost.

6. Incoterms, customs and who pays what

Shipping terms decide where risk and cost move from seller to buyer. EXW (ex-works) means you collect from the seller’s premises and handle everything from there. FCA and FOB move risk at the carrier or port. DAP delivers to your door but leaves import duty to you; DDP includes duty and taxes.

For the UAE, budget the 5% customs duty plus VAT on hardware unless the machine stays in a free zone, and confirm the declared value matches the real price. Never agree to an under-declared invoice: it shifts the legal risk to you and voids most cargo insurance.

Insure the shipment for its full value. ASICs are heavy and fragile; original boxes or proper foam and fixed PSUs prevent most transport damage.

7. Pay safely

• Pay a company, not a person: bank transfer against an invoice that shows the seller’s legal name and the machine serials.
• Be wary of crypto-only payment to a personal wallet. It is irreversible and the most common thread in reported miner scams.
• Split the payment where you can: a deposit, then the balance after the pool test or inspection.
• Segments never asks buyers to pay to a personal wallet or account. Hosted sales on the Segments marketplace are paid by Segments invoice.

8. Use an independent inspection

If you cannot see the machine yourself, pay someone who can. A Segments inspection checks serials against the ad, runs the machine on a known pool, measures hashrate against nameplate, records chip temperatures, fan and board status, and publishes a dated report with photos and video on the ad.

Inspected ads carry a badge and the report stays attached to the listing, so the next buyer benefits from it too. Machines already hosted at a Segments site go further: their hashrate and uptime come from our own telemetry, and ownership moves without the machine ever leaving the rack.

Quick checklist

1. Price per TH is within the range of its efficiency band.
2. Serial stickers, control board and hashboards match the ad and each other.
3. Warranty status checked with the manufacturer.
4. Kernel log shows full chip counts on every chain.
5. Pool test of 24 to 48 hours on your own pool account.
6. DOA terms, incoterm and declared value agreed in writing.
7. Payment to a company against an invoice, ideally in stages.
8. Independent inspection, or a machine hosted at a site that can prove its output.