Dell's Built-in Diagnostics Explained (SupportAssist & Pre-Boot Assessment)
Beginner
Dell
Applies to: Windows 7, Windows 10, Windows 11
Dell
Applies to: Windows 7, Windows 10, Windows 11
A hardware test that runs independently of Windows, useful when you suspect a physical fault rather than a software problem.
Before you start: save any open work and note down what you were doing when the problem started — that context helps if you need to search further or ask for help.
- Restart the Dell and tap F12 repeatedly at startup to reach the boot menu, then choose "Diagnostics" from the list of options — this runs Dell's Pre-Boot System Assessment (ePSA), which tests hardware directly, before Windows even loads.
- Let the full test run rather than stopping partway — it checks memory, storage, and several other core components in sequence, and a fault in a later stage won't show up if you cancel early.
- Write down any error code shown at the end — Dell's diagnostics produce a specific code (often starting with a component identifier) that's far more useful for support or warranty purposes than a general description.
- If Windows is working normally, Dell SupportAssist (usually pre-installed) offers a similar hardware scan from inside Windows itself, plus driver and update checks, without needing to restart.
- A hardware test that passes doesn't rule out every possible problem — it specifically confirms the components it tests are functioning, which is still useful information even if your actual issue turns out to be software-related.
Still not fixed? Send us the details and we'll help you dig further, or browse related guides in Dell.
Frequently Asked Questions
How long does the full Dell diagnostic test take?
It varies with your hardware, but typically 10-30 minutes for a full pass. Memory and storage tests tend to take the longest of the individual components checked.
If the diagnostic passes, does that mean nothing is wrong?
It means the specific components tested are functioning correctly — it doesn't rule out a software-level cause for whatever symptom prompted you to run it in the first place.
Related guides
How to Enter BIOS or the Boot Menu on a Dell Computer
The right key, timing, and what to do if tapping it doesn't work.
Where to Get Official Dell Drivers (and Avoid Fake Ones)
Dell Command | Update and Dell's own support site — not a third-party "driver updater" tool.
How to Factory Reset a Dell Using SupportAssist OS Recovery
A recovery environment built into the machine, independent of Windows — useful when Windows itself won't start.