One drive failing FakeFlashTest’s Quick Size Test is a verdict on that drive. Every drive failing — including one you know is genuine — is a verdict on something else, and recognising that is the key to this entire guide: when every drive fails, the suspect changes. You are no longer hunting fake drives. You are hunting interference on your own computer.
This is not guesswork. The developer of FakeFlashTest addresses this exact pattern: if the Quick Size Test fails every drive, security software or a driver is likely interfering with the tool, and the advised solution is to run FakeFlashTest in Windows Safe Mode. This guide explains why that works, how to do it, and how to confirm the diagnosis. Keep the genuine tool handy via our download page, and keep our Quick Size Test guide open for how the test should behave normally.
Why security software and drivers can break the test
The Quick Size Test does low-level work: it writes 512-byte marker blocks at intervals across a drive and reads them back, starting from the end of the reported capacity. Tools that operate at that level look, to protective software, similar to things protective software exists to stop. A security program or a storage-related driver that intercepts, delays, or blocks those operations can corrupt the test’s view of the drive — writes that never landed, reads that were mediated — producing failures that describe the interference, not the drive.
The tell is the pattern. Interference does not care which drive is inserted, so it fails genuine drives and fake drives with equal enthusiasm, often quickly and in similar ways. A single fake, by contrast, fails on its own merits while known-good drives tested on the same setup pass. Before you conclude anything about a batch of drives, test one drive you trust completely — a genuine drive from a reputable purchase that has been in reliable service. If that drive fails too, stop condemning drives and fix the test environment.
The Safe Mode fix, step by step
Safe Mode starts Windows with a minimal set of drivers and services. The security software and third-party drivers that interfere with low-level testing are, by design, not loaded — which is exactly the environment the developer advises for a clean run. On Windows 10 and 11, the standard route is: hold Shift while clicking Restart from the Start menu; in the recovery screens that follow, choose Troubleshoot, then Advanced options, then Startup Settings, then Restart; when the list appears, press the key for Safe Mode (plain Safe Mode is sufficient — you do not need networking for a local test, and networking adds back components you are trying to exclude).
Once in Safe Mode, the desktop will look stark and low-resolution; that is normal. Plug in the drive directly, confirm Windows assigns it a letter, and run FakeFlashTest as administrator — the administrator requirement from our guide on FakeFlashTest showing no drives still applies in Safe Mode. Select the correct drive letter with the usual care (the Quick test is destructive; the drive should be empty or backed up) and run the Quick Size Test. Then restart normally when you are done; Safe Mode is a one-boot diagnostic environment, not a state your PC stays in.
How to confirm the diagnosis
Run two tests in Safe Mode if you can: the known-good drive first, then the suspect drive. There are three informative outcomes. If the known-good drive now passes, the interference diagnosis is confirmed — your normal Windows environment was corrupting the tests, and every fail recorded there should be discarded and retested. If the suspect drive then also passes in Safe Mode, it was a victim of the same interference; treat it as unproven rather than fake, and consider a full test for confidence. If the suspect drive still fails in Safe Mode while the known-good drive passes, the failure is travelling with the drive, not the PC — that is a genuine verdict you can act on, with the log as evidence.
Back in normal Windows, you can optionally identify the interfering component by elimination — pausing individual security tools’ real-time features within their own settings, one at a time, and retesting the known-good drive — but you never need to solve that mystery to get a trustworthy result. Safe Mode already gives you one. Never respond to interference by permanently disabling your security protection for everyday use; the diagnostic mode exists precisely so you do not have to.
What not to conclude, and what to do next
Do not conclude that several drives bought from different places all turned out fake simultaneously — simultaneous universal failure is the signature of a local cause. Do not return a drive as counterfeit on the basis of a test run in an environment where a known-good drive also fails; that evidence would not hold up, and it is not fair to the claim. And do not keep re-running the same test in the same environment expecting a different pattern; interference is consistent until the environment changes.
Instead: Safe Mode, known-good drive as control, suspect drive as test, logs screenshotted. A fail that survives a clean environment is a result you can trust and use. The tools and guides are all linked from the download page hub — and with the control-drive habit built in, you will never again mistake a grumpy driver for a drawer full of fakes.