As an aside, this wouldn't be an audible alarm - more it'd be a warning on boot up if the case had been opened. It's commonly used in office environments or in industrial servers where if someone's tampered with the insides of your machine without you knowing about it, you don't want the thing booting up until you've found out exactly what's going on!The Video did help and I discovered something new ...I didn't realize the Micro SW was actually an alarm system...I can't even find this pin on the mobo...I won't even bother installing it ...doubt it was in the first place...I never heard an alarm.
It may have been connected originally and disabled in the BIOS, or it may not have been connected at all. Either way, it's a feature that most home users can safely ignore and leave unplugged!