Computer Repair · November 11, 2026 · ComputerKing Team

The SSD in Your Drawer May Be Quietly Losing Data: What a Year Without Power Risks

An SSD without power does not keep your data forever. NAND flash stores data as trapped electric charge, and the insulation around each cell is not perfect, so charge slowly leaks away; the JEDEC standard only requires a consumer SSD to retain data for one year unpowered at 30 °C. Older drives and drives with high write counts lose data faster. This guide covers which drives are most at risk, how to do a periodic power-on check, and what real long-term backup looks like. Pricing is quoted case by case.

Key takeaway

An SSD without power does not keep your data forever. NAND flash stores data as trapped electric charge, and the insulation around each cell is not perfect — charge slowly leaks away, voltages drift, and what gets read back starts to be wrong. The JEDEC JESD218 standard only requires a consumer SSD to retain data for one year without power at 30 °C. Older drives and drives with high write counts lose data faster. Tests also show that drives powered on periodically hold up far better than drives left alone. This guide covers which drives are most at risk, how to do a periodic "power-on check", and what real long-term backup looks like.

1. What the news says: SSDs lose data without power too

• Reports on 6 November (MakeUseOf) and 7 November (XDA) point out: SSDs, hard drives and USB sticks all slowly lose data over time, at different rates for different kinds.
• The problem is not wearing out, it is sitting unused: a drive in daily use has power and is read and written regularly; a drive left for months in a drawer, a storeroom or an old machine can quietly lose data instead.
• This is not theory: one YouTuber ran a two-year test, and another user ran a one-year comparison — both point the same way: the longer a drive sits unpowered, the worse its data integrity gets.
• This is not a reason to stop using SSDs: a drive in daily use, powered and read regularly, is not the high-risk case here. This article is about the drive you have not touched for a long time.

The point is not to stop using SSDs — the drive in daily use, powered and read regularly, is not the high-risk case. What deserves attention is the drive that has been 'put away for a long time': the SSD pulled from an old machine, the external drive filled with photos and then shelved, the USB stick used for last year's backup and forgotten since. These drives will not tell you they are in trouble; you only find out on the day you need the data back and it will not open.

2. Why it happens: leaking charge

• How NAND flash stores data: each cell holds trapped electric charge, and the amount of charge decides what value is read back.
• The insulation is not perfect: the insulating layer around each cell slowly leaks charge, voltages drift, and the value read back goes wrong.
• Wear makes it worse: every write-and-erase cycle pushes electrons through that insulation and damages it slightly. The more a drive has been written to, the weaker the insulation and the faster the leak.
• Heat is an accelerator: the hotter it gets, the faster charge leaks. The JEDEC standard only requires a consumer SSD to hold data for one year unpowered at 30 °C; raise the temperature and that window shrinks. In Hong Kong, an indoor room can easily pass 30 °C in summer, so where you store a drive matters.
• Why a drive in use is fine: while an SSD is powered and running, its controller corrects errors and tidies data, so leaking charge can be fixed between reads and writes. Without power, there is no correction at all.

In other words, an SSD keeps data with physical electric charge, not magic. Charge leaks because of the material itself, not because of poor quality — even an expensive drive leaks, only more slowly. Once you understand that, you can see why 'put it aside and ignore it' is the worst way to store data: you are not only leaving the data unprotected, you are taking away the controller's chance to correct errors.

3. Which drives are most at risk: TLC/QLC, old drives, heavily written drives

• QLC is weakest: most consumer SSDs use TLC or QLC. QLC stores four bits per cell, has the most voltage levels and the least margin for error, and the weakest long-term retention. As a rough guide, QLC holds data unpowered for about a year, TLC for up to about three years, MLC for about five and SLC for about ten — these are approximate figures quoted by XDA, and real results vary by model.
• Drives with high write counts: a drive that has been written to heavily has worn insulation and loses data faster once unpowered.
• Old drives: a drive already several years old has aged cells and holds data worse than a new one.
• USB sticks are the same: a USB stick is also NAND flash and has the same leakage problem. Cheap sticks use poorer material, so do not treat one as a long-term archive.
• Not every drive fails: one user bought ten Kingston USB sticks in 2020, filled them with data and kept them in a dry, stable environment; by early 2026, five had been tested and none showed any damage. Environment and drive quality make a big difference.

4. What the tests show: powered on versus left alone

• YouTuber HTWingNUt's two-year test: four 128 GB TLC SSDs filled with 100 GB of data and verified with MD5 hashes. Two were "torture-tested" first with 280 TB written — far beyond their official 60 TBW rating — then all four were stored in anti-static bags in a climate-controlled room and tested once a year. After one year, all four passed; after two years, one of the heavily worn drives had four corrupt files, and verifying its data took more than 42 minutes instead of 10. The conclusion: the harder a drive has been pushed, the more likely it is to corrupt once left unpowered.
• User Carnildo's one-year comparison: three cheap USB sticks with the same photos, stored in an attic, in a room left unplugged, and in a room plugged in periodically. After one year, the attic stick had 138 corrupted images, the indoor unplugged stick had 773, and the periodically plugged-in stick had only 6.
• The shared lesson of both tests: drives that are powered on and read periodically hold up far better than drives left alone. Powering on is not magic — it gives the controller a chance to correct errors, and it lets you spot a problem early.

Neither test had a large sample, so neither can be taken as a guarantee, but they point the same way: drives that are powered and read regularly hold up clearly better than drives left alone. What stands out most is Carnildo's periodically plugged-in stick — the damage did not halve, it fell from hundreds of images to single figures. A difference that large is hard to call a coincidence.

5. What Hong Kong users should watch: heat and humidity

• Heat: the hotter it is, the faster charge leaks. Do not store backup drives by a sun-facing window, in a hot storeroom, in a car boot or in an attic.
• Humidity: Hong Kong is humid, so long-term storage needs moisture protection. A dry box, or a sealed bag with desiccant, beats a random drawer.
• Never rely on one drive: whether it is an SSD, a USB stick or a hard drive, a single drive is not a long-term archive. The real danger is not that a drive can fail — it is having only one copy when it does.
• Hard drives have their own problems: a traditional hard drive left unpowered for years can seize up — if the bearings stick, it cannot spin — and its magnetism slowly fades too. A hard drive is not the "safe for years" answer.

Hong Kong's problem is heat and humidity arriving together. Summer indoor temperatures easily pass 30 °C — exactly the threshold temperature in the JEDEC standard — and the damp spring season adds oxidised contacts and moisture on circuit boards, all extra risk. Storage does not need to be laboratory-grade, but it should at least be cool, dry and stable.

6. The right approach: power on periodically, and follow 3-2-1 backup

• Plug in every few months: take long-stored SSDs, USB sticks and external hard drives, plug them into a computer and open a few old files to confirm they still open. You do not need a full-disk verification — files opening and photos displaying is already a basic check.
• Check before putting them away again: if a file will not open or a photo is damaged, copy it back from another backup at once — do not wait.
• The 3-2-1 rule: keep at least three copies of important data, on two different kinds of media, with one copy off-site (for example in the cloud, or at another address). Do not make all three copies the same kind of SSD.
• Do not treat a backup drive as an archive: a backup drive's job is to save you when something goes wrong, not to sit untouched for ten years. A backup only counts as real if you have checked that it restores.
• Before retiring an old drive, back it up first: do not throw away or format an old drive directly. Copy the data to a new drive, confirm the files open there, and only then deal with the old one.

Many people think buying another drive and copying the files counts as a backup, but if all three copies are the same kind of SSD, kept in the same drawer and never checked for years, that is only the same risk copied three times. A real backup is not about how many copies you made, but about different media, different places and regular verification — miss one of those and the protection is incomplete.

7. When to bring the drives in

• An old SSD is not recognised when plugged back in, or is recognised but its files cannot be read.
• A backup drive has damaged files, and the other copy is incomplete.
• You are not sure which data is on which old drive, or you want to consolidate several old drives into one reliable backup setup.
• In these cases, do not keep plugging and unplugging, and do not format anything — bring the drives in for a check. Pricing is quoted case by case.