my computer back fires

i was trying to take a test on a free online computer class. i signed in , keyed in the test, waited, answered the 1st. ? waited,

then it sounded like a bomb.
i've be hearing it for a while before i recognized it.

what is it?

what does it sound like?

you ever hear a computer game explosion

yeah

well thats it.

mmmm could be a few things

you might as well know that i don't know much about p.c.
so where do we begin?

You sure you don't have rambo on in the background?

well could be one of the fans or a mechinical part i suggest you take it to a computer store so they can take a look at it

how are you today?

the store comes to me if i use my computer guy.

ok he will need to look it over because as you said you dont know much about computers