The Startup Memory Tests option in later versions of the Memory control panel in Mac OS 8 (e.g. Mac OS 8.5) is accessible only if the command and option keys are held down when the Memory control panel is opened.
If the On option is selected, an integrity test of the physical RAM on your Macintosh takes place at startup. Should there be any errors, a message appears. The RAM test takes longer for Macs with more memory; up to two minutes may be used by this test.
Users confident that their RAM chips are working fine can turn off this option.