I used to work in a notebook repair centre, when they make a lot of noise its normally because something is rubbing against the CPU fan, some wires or a screw than has become loose. Open it up and have a look inside, unless you risk invalidating your warranty.
Staurm Reviewed by Staurm on . my laptop is hissing at me it also won't turn on unless I hold the button down for long time, until it finally makes this screeching noise, then it turns on lol that reminds me of an ex! :(what's wrong little computer? Rating: 5