Windows Memory Diagnostic

What it does

Windows Memory Diagnostic runs a series of pattern tests against your installed RAM outside of the normal Windows environment, since testing memory that's actively running the OS isn't reliable. It reboots into a minimal diagnostic environment, runs its tests, then boots back into Windows and reports results.

How to run it

1. 1Press Windows key, type Windows Memory Diagnostic, and open it (or run mdsched.exe from the Run dialog).
2. 2Choose Restart now and check for problems (recommended) to run the test immediately, or schedule it for the next restart.
3. 3The PC reboots into a blue diagnostic screen and runs the default test automatically; press F1 during this screen to choose Basic, Standard, or Extended test mix and number of passes.
4. 4After the test completes, Windows boots normally and shows results either immediately in a popup or, if missed, in Event Viewer under Windows Logs > System, filtered for source MemoryDiagnostics-Results.

Interpreting results

A clean pass with no errors means the tool didn't detect faults during that run, but doesn't guarantee your RAM is fault-free — intermittent errors can be missed by a short test. Any reported hardware errors indicate faulty or improperly seated RAM and should be treated seriously.

When to run it

• Random blue screens (especially MEMORY_MANAGEMENT or similar stop codes) with no obvious software cause.
• System instability after installing new RAM.
• Unexplained application crashes or data corruption not tied to a specific program.

Limitations

The built-in tool runs a limited set of passes in a reasonable time; it can miss intermittent faults that only show up under extended, repeated testing. For more thorough hardware validation, see the dedicated RAM testing guide.