why is this strange non-stop alarm sound(like fire alarm) from computer cabinet ?

hari2202

Honorable
Aug 4, 2013
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10,690
the computer is running smoothly , its powered on and i have been working on it for some few hours .
i just moved out of the desk chair to have some fresh air .

all of a sudden there is some alarm like noise , it was like a fire alarm non stop and continuous . i was in the next room and i am able to hear that sound . i rushed into room to figure out where the sound comes from . shockingly it comes from my computer cabinet ..

then i hibernated the PC as fast as i can and the sound goes off . Then i again powered on my PC to check sound still persists but no sound this time BUT it took some time for PC to startup , especially the monitor is blank for few minutes and dvd burner is not working at all , no led light from DVD burner and then i again turned off the PC .....

After that i turned on the PC now and everything is working fine now , no sound , boots up in time and dvd drive is also working ..

but why does such a sound come from the PC , what may be the reason ? will it come again ?