Iv been long time pc user but switch to laptop and not very into this thing yet so to ask ya.Some say its perfectly normal,but i dnt recall hearing this when bougth the laptop week ago.Its acer aspire 5750g i3 2.10ghz 4gb ram 500HDD
Sounds like your fan. May be its not set right or is loose or bearings are shot. Try and take a look at your fan, it should be accessible, see if you can see anything not right. If not, go back to Acer and see if they can help.
The sound puts me in mind of a fan blade rubbing up against a foreign item (a piece of cardboard or other debris?). Or maybe something internal in the laptop near the path of the spinning fan blade - a wire drifting over near the fan?
A bright light and a visual inspect of the exhaust port before diving into the internals?
hahah now sound is less noticable when not playing game or watching video.Lol myself was afraid to open the laptop since its all electronics in there.So i blow up nicee air on it and seems it is part gone.