Used ASIC Condition-Grading Standard & Pre-Purchase Inspection Checklist

Buy a used ASIC by its grade, not its photo. D-Central grades used miners on a four-tier standard — A, B, C and Parts — where a grade is a promise about hashrate, thermals, remaining life and a defensible warranty. Below is the full standard plus a pre-purchase inspection checklist that links the exact reference you need for every check.

Quick answer

A used ASIC should be bought by its grade, not its photo. D-Central grades used miners on a four-tier standard — A (excellent, near-new), B (good, serviceable), C (functional, high-hours), and Parts (donor / as-is) — where a grade is a promise about hashrate, thermals, remaining life and a defensible warranty, in that order. Because it is a standard we author rather than data we measure, there is nothing to fabricate: the rubric itself is the product, and we hold our own refurbished inventory to it. Pair it with the pre-purchase inspection checklist below, where every check links the exact D-Central reference you need to judge it.

The lowest criterion a unit meets is its real grade. Insist on a live status page showing hashrate and per-chip temperatures; treat "no live proof" and "recently deep-cleaned" as automatic downgrades; and match the asking price to the used-price-index band on a $/TH basis. Grade A earns a real short warranty; Grade C is cheap watts for a heater or a tinkerer; Parts is for donors only — never a first miner.

The D-Central condition-grading standard

The grading standard below is D-Central's own definition, not a measured dataset — which is precisely why it is trustworthy: there is nothing to fabricate. A grade is a promise about hashrate, thermals, remaining life and a defensible warranty, in that order. We hold our own refurbished inventory to it ("graded to the D-Central standard"), and we publish it openly so any buyer or seller can use the same yardstick.

Grade	Hashboards & hashrate	Thermals	Remaining life	Defensible warranty	Price band
AExcellent — near-new / low-hours	All hashboards at or above the model's rated hashrate; zero dead chips; accept-rate normal; no board previously reflowed or repaired.	All chip temps in the healthy band under sustained load, even spread across the board (no hot corner); no evidence of past overheating (discoloured PCB, lifted heatsinks).	Full remaining service life; typically <6 months runtime or genuinely refurbished to as-new.	A 30–90 day parts-and-labour warranty is reasonable and defensible.	Top of the used band — close to the used-price index high for the model.
Cosmetic: Clean, no immersion/oil residue, no corrosion, intact seals and labels, original PSU with matching hours. · Best for: A buyer who wants a near-new unit and predictable life without paying new-unit lead times or price.
BGood — serviceable, moderate hours	Within ~5% of rated hashrate; at most a small number of dead chips already compensated by autotuning; may have one professionally reflowed board that now passes.	Temps in the acceptable band; a slightly warmer board or a fan working harder is acceptable if hashrate and accept-rate hold.	Solid remaining life; the mainstream used unit — expect routine maintenance (fans, paste) over its remaining run.	A 14–30 day functional warranty (DOA-style) is defensible; full-term warranty is not.	Middle of the used band.
Cosmetic: Light wear, dust, minor cosmetic marks; no active corrosion; PSU healthy; seals may be broken from legitimate servicing. · Best for: The value buyer who accepts moderate hours and basic maintenance in exchange for a real discount.
CFunctional — high-hours / as-described working	Runs and hashes but below rated (dead chips, one weak board, or de-rated to stay stable); accept-rate acceptable but margins are thin.	Runs hot or needs elevated fan speed / lower power to stay stable; a hot board or uneven spread is expected and must be disclosed.	Limited remaining life; best as a heat-reuse unit, a parts donor that still runs, or a cheap entry rig for a low-power tune.	Sold working / tested-on-arrival only — no meaningful warranty beyond DOA. Firmware unlock or repair may be needed.	Bottom of the used band.
Cosmetic: Heavy wear, dust, possible light surface corrosion; PSU may be aftermarket or high-hours; expect to service or replace fans and paste immediately. · Best for: The heat-reuse or tinkerer buyer who wants cheap watts and can do their own maintenance.
Parts / As-IsParts or as-is — not sold as working	Does not reach a usable hashrate, has one or more failed boards, or is untested. Value is in salvageable boards, PSU, control board, frame and fans.	Not applicable — may not run, or runs only intermittently.	None as a whole unit; value is per-component for repairs (cross-link the repair-parts and hashboard references).	None. Sold explicitly as-is / for parts, with no working claim of any kind.	Salvage value only — priced on recoverable components, not hashrate.
Cosmetic: Any condition, including immersion units, water-damaged, or corroded. · Best for: Repair shops and DIY fixers sourcing donor boards, PSUs and control boards — never a first miner.

🟠 Graded to the D-Central standard. We hold our own refurbished inventory to this rubric — and publish it openly so any buyer or seller can use the same yardstick.

Pre-purchase inspection checklist

Use it in two passes. First, run the pre-purchase inspection checklist — each item links the exact D-Central reference you need to judge it (fault localizer, operating-temperature, PSU, fan-spec, firmware-lock, reliability index). Then map what you found onto the grade table: the lowest criterion a unit meets is its true grade. A unit that hashes at rate but hides an ex-immersion board is not Grade A — it is Grade C with a disclosure. When in doubt, grade down and price to the used-index band.

Identity & authenticity

□ Confirm the model and hashrate match the listing, and the serial/label matches the control board.

Red flag: Repainted shroud, mismatched labels, a serial that doesn't match the model, or a 'S19 Pro' that is really a plain S19 (114 vs 76 chips per board).

Model swaps and relabels are the most common used-market fraud. Cross-check the real spec before you pay. Hashboard reference (chips per board by model) →

□ Ask for a live screenshot of the miner's status page showing hashrate, per-board chip count, and temperatures under load.

Red flag: Seller refuses live proof, sends only stock photos, or the screenshot hides the chip/temperature columns.

A working unit can always show its own status page. No live proof is itself a red flag. Miner API / status reference →

Hashboard health

□ Compare actual hashrate to the model's rated hashrate, and check for dead or missing chips on any board.

Red flag: Hashrate well below rated, a board reading far fewer chips than spec, or frequent hardware errors in the log.

Dead chips and a de-rated board are the difference between a Grade A and a Grade C unit — and drive the repair cost you may inherit. Hashboard fault localizer →

□ Look for evidence of prior board-level repair — reflowed chips, replaced components, flux residue.

Red flag: Undisclosed rework on a unit sold as Grade A; sloppy reflow or bridged pads (see the reball reference for what good work looks like).

A professionally repaired board can be fine, but undisclosed repair on a 'like-new' unit is misrepresentation and shortens life. BGA reball & reflow reference →

Thermal signs

□ Check per-chip temperatures under sustained load and confirm an even spread across each board.

Red flag: A hot corner or hot board, chip temps near throttle, or a discoloured/browned PCB from past overheating.

Uneven or high temps predict the next failure. A unit that only stays stable de-rated is a Grade C at best. ASIC operating-temperature reference →

Power supply

□ Confirm the PSU model matches the miner and the input voltage (120 V vs 200–240 V), and that it is the original or a proper equivalent.

Red flag: A 120 V-only PSU on a unit that needs 200–240 V, an aftermarket PSU with no spec, or scorch marks / a burnt smell around the connectors.

A wrong or failing PSU is a fire risk and a hidden replacement cost; APW12/APW17-class supplies are 200–240 V only. ASIC PSU reference →

Fans & cooling

□ Confirm all fans spin freely, report correct RPM, and match the model's fan spec; listen for bearing noise.

Red flag: A seized, wrong, or noisy fan; RPM readings missing; fans running at 100% just to hold temperature.

Fans are consumable and cheap, but fans pinned at max to stay cool signal a deeper thermal problem. ASIC fan-specification reference →

Immersion & water damage

□ Inspect for oil/immersion residue, water staining, corrosion on connectors, or a cleaned-up ex-immersion unit sold as air-cooled.

Red flag: Oily film, white/green corrosion, or a suspiciously 'deep-cleaned' board — ex-immersion units are Grade C or Parts, never Grade A.

Immersion and water exposure change the remaining-life story entirely and must be disclosed and graded down. Immersion cooling fluids reference →

Firmware & lock status

□ Confirm the firmware is stock or a disclosed known build, and check whether the model/firmware is prone to vendor locking or bricking.

Red flag: A locked or unknown-custom firmware, a unit stuck in a bootloader, or a model on the firmware-lock tracker with an unresolved lock.

A firmware lock can turn a working unit into a repair job; know the lock status before you buy. ASIC firmware-lock tracker →

Expected reliability

□ Check the model's expected reliability tier and known failure modes for its generation before committing.

Red flag: A generation with a poor reliability record priced as if it were a safe long-life unit.

Some generations simply fail more; factor the model's reliability tier into the grade and the price you will pay. ASIC reliability index →

Price sanity

□ Compare the asking price to the used-price index band for the model and condition, on a $/TH basis.

Red flag: A Grade C price attached to a Grade A claim, or an asking price above the used-index high for the model.

The grade sets the band: a fair used price tracks condition. Anything above the index high for the model needs justifying. Used-ASIC price index →

Why D-Central publishes this. The used-ASIC market is where a first-time buyer is most likely to get burned: a relabelled model, a de-rated board sold as full-hashrate, an ex-immersion unit deep-cleaned and sold as air-cooled, or a firmware-locked miner that becomes a repair job the week after it arrives. D-Central lives on the repair bench, so we know exactly what separates a good used unit from a bad one — and we have turned that into a public standard anyone can cite.

Open data (CC BY 4.0): CSV · JSON · API: /wp-json/dc/v1/used-asic-grading

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Last reviewed July 18, 2026.