What is the difference between original, white-lot and black-lot NAND flash?
NAND dies are graded by how much testing they passed before being sold on, and the market describes three tiers. Original grade comes from the manufacturer fully tested and meeting full specification. White-lot describes dies that did not pass full original-spec testing but pass a looser specification, sold through third parties rather than under the original brand. Black-lot describes dies that failed testing and should have been scrapped, re-entering the market through uncontrolled channels. The practical consequence for a buyer is not speed but risk: grade determines how much of your production batch will fail in the field, and whether you have any recourse when it does.
The three tiers
The grading system exists because a wafer is not uniformly good. Dies are tested at wafer level and sorted. What happens to the ones that do not pass varies enormously.
| Grade | What it is | What it means for a buyer |
|---|---|---|
| Original | Fully tested by the original manufacturer, meets full published specification | Predictable behaviour, documented endurance, recourse through the supply chain |
| White-lot | Did not pass full original-spec testing, but passes a looser specification; sold as unbranded or third-party marked die | Usually cheaper; endurance and retention are less certain; traceability is weaker |
| Black-lot | Failed testing and characterised as scrap, re-entering the market through uncontrolled channels | The cheapest option and the highest field-failure risk; effectively no recourse |
Why it matters more than speed
Grade is rarely visible in performance testing on a new drive. A fresh white-lot drive benchmarks close to an original one. The difference appears later, as elevated failure rates, data retention problems and units that stop being readable.
That delay is what makes grade a commercial risk rather than a technical footnote. By the time the failures show up, the product is in the field and the cost is not the drive — it is the return, the replacement and the reputation.
It also affects whether you have recourse. Original-grade material is traceable back through the supply chain. Black-lot material is by definition outside those channels.
Why the market is sensitive to this right now
When memory supply is tight, the incentive to sell lower-grade material into places that expect original grade increases. The 2026 supply situation — with AI data centres absorbing a large share of memory output — is exactly the kind of market where buyers get offered material of unclear provenance.
H2testw will not catch this. It verifies capacity, not grade. A black-lot drive with correct capacity passes the test today.
Questions to ask any supplier
Grade is not something you can inspect on delivery, so it has to be established through the conversation before you order.
- Which silicon sources do you buy from, and can you name them for this specific project?
- Is the die original, white-lot or black-lot for the quote you have given me?
- What die package format is used — TSOP, BGA, LGA, COB or eMMC?
- Which controller solution is used, and why that one for my application?
- What is your process if a batch shows an elevated failure rate?
Sources
- NAND Flash Chip Recycling: White-Lot vs Black-Lot Grading — memoryrecycle.com
- NAND Flash Chip Grades Explained — usbtalk.net
Figures quoted on this page are from the published reporting listed above. Where a number is an estimate rather than a published figure, it is described as approximate.
Frequently asked questions
Can I tell the grade by looking at the drive?
Generally no. Markings can be absent or uninformative, and there is no reliable visual test. Grade is established through supplier disclosure and supply-chain traceability, not inspection.
Is white-lot always bad?
Not necessarily. For workloads that are not write-intensive and where field failure is cheap to fix, a lower grade can be a defensible cost decision. It becomes a problem when it is sold as original grade, or used where the buyer is exposed to field failure costs.
Does H2testw detect black-lot flash?
No. It tests whether the capacity is real, not the grade of the silicon. A black-lot drive with honest capacity will pass.
What grade does WINTEL use?
We supply A+ grade flash, sourced from SanDisk, Toshiba, Micron, SK Hynix, Intel and Samsung. Ask us for the sourcing breakdown on a specific project and we will confirm it for that quote.
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