How to Check Used SSD Health: TBW, SMART Attributes & CrystalDiskInfo Guide
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Solid-state storage is one of the most cost-effective components to source on the UK second-hand market. Fast PCIe 4.0 1TB and 2TB NVMe drives (such as the Samsung 980 Pro, WD Black SN850X, or Crucial P5 Plus) frequently sell for £40 to £75—roughly 40% to 50% below new retail prices.
Unlike spinning hard disk drives with delicate mechanical platters, solid-state drives have zero moving parts, making them physically immune to shipping shocks. However, NAND flash memory has a finite electrical lifespan governed by program/erase (P/E) cycles. If you unknowingly purchase a drive that spent two years plotting Chia cryptocurrency or running heavy enterprise database writes, its flash cells may be exhausted.
Demystifying TBW: What Do the Numbers Mean?
TBW (Terabytes Written) represents the total cumulative volume of data that can be written to the NAND flash before the manufacturer warranty expires. Modern TLC drives are exceptionally durable:
| Popular SSD Model | Capacity | Manufacturer TBW Rating | Typical UK Used Price | Normal Gaming Wear (3 Yrs) |
|---|---|---|---|---|
| Samsung 980 Pro / 990 Pro | 1TB / 2TB | 600 TBW / 1,200 TBW | £45 – £75 | 25 – 45 TBW (~5% used) |
| WD Black SN850X | 1TB / 2TB | 600 TBW / 1,200 TBW | £48 – £80 | 30 – 50 TBW (~6% used) |
| Crucial P3 / P3 Plus (QLC) | 1TB / 2TB | 220 TBW / 440 TBW | £30 – £55 | 30 – 50 TBW (~15% used) |
| Kingston NV2 (Entry Budget) | 1TB / 2TB | 320 TBW / 640 TBW | £28 – £48 | 35 – 55 TBW (~12% used) |
For general storage buying advice, consult our dedicated guide on Buying a Used SSD in the UK.
The 4 Critical SMART Attributes in CrystalDiskInfo
When you launch CrystalDiskInfo, ignore the dozens of raw hexadecimal values and focus intently on these four lines:
1. Health Status & Percentage Remaining
Target: 90%+Calculated by the SSD's memory controller based on the ratio of actual host writes to rated endurance. A drive showing 94% Good has only consumed 6% of its rated lifespan. Avoid drives showing “Caution” or below 75%.
2. Available Spare & Percentage Used (NVMe Spec)
Target: 100%Modern NVMe controllers allocate an over-provisioned pool of reserve flash blocks. When a NAND block wears out, the controller remaps it to a spare block. If Available Spare has dropped below 100%, original blocks are already degrading.
3. Media and Data Integrity Errors
Target: Exact ZeroThis counts instances where the drive encountered uncorrectable read or write errors that internal ECC (Error Correction Code) could not repair. If this number is greater than 0, do not buy the drive.
4. Power On Hours & Power On Count
Usage HistoryA typical home gaming PC accumulates around 1,500 to 2,500 power-on hours per year. If a drive shows 18,000 hours (over 2 years of continuous 24/7 uptime) combined with massive write figures, it was used in a server or mining farm.
Beware Fake NVMe Drives & Label Swapping
Always run a quick benchmark in CrystalDiskMark. A genuine PCIe 4.0 drive will achieve sequential read speeds exceeding 5,000 MB/s to 7,000 MB/s. Fake drives will choke at 1,800 MB/s to 2,400 MB/s.
Secure Erase & TRIM: Restoring Factory Speed
When you receive a used SSD, old deleted files often leave residual charge on NAND blocks, degrading write speeds. Perform a hardware-level NVMe Secure Erase / Sanitize via your motherboard BIOS (often found under “Tools” or “Storage Utilities”). This issues a voltage flush to all flash cells simultaneously, restoring fresh factory write performance.
Frequently Asked Questions
Can an SSD's SMART data be reset or faked by a seller?
Standard users cannot reset SMART data; it is stored inside non-volatile controller EEPROM. However, sophisticated scammers with specialized MPTool software can re-initialize generic Phison or Silicon Motion controllers. Tier-1 drives with proprietary encrypted controllers (like Samsung and WD Black) cannot have their SMART data reset.
Should I avoid QLC SSDs on the used market?
QLC (4 bits per cell) drives have significantly lower write endurance (~200–400 TBW for 2TB) and suffer from severe write slowdowns once their SLC cache fills. We recommend sticking to TLC (3 bits per cell) drives like the Samsung 980 Pro or Kingston KC3000 for primary gaming and OS drives.
Does a used SSD need a heatsink?
Fast PCIe 4.0 and PCIe 5.0 drives run hot (65°C–80°C under load) and will thermally throttle without a heatsink. Ensure your motherboard has integrated M.2 heatsink shields, or purchase a £5 low-profile copper heatsink.
Source Inspected SSDs on Koukan
Every storage drive sold on Koukan includes escrow buyer protection. Check SMART health and verify CrystalDiskMark speeds on your own system before funds are finalized.
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