Engadget
What happens when you run the Windows Memory Diagnostic tool?

The Windows Memory Diagnostic utility, built into Windows, restarts the PC outside the OS to run configurable Basic, Standard or Extended memory tests that repeatedly write and read data, flagging any discrepancies as RAM errors. After the reboot, test outcomes are logged in the System section of Event Viewer, where users can filter for the Memory Diagnostic entry to view pass counts, error details and overall results.