The death chime from the Macintosh Quadra 840 AV, my beloved workstation for two or three years in college. Basically, if you powered on and a hardware check failed, this is what you’d hear, and you’d probably also see a Sad Mac.

If this isn’t the most excellent sound ever to be burned into the ROM chip of a personal computer, then I don’t know what is.

(audio file ganked from Mactracker)