Hello My laptop is 6 year-old (Hp pavillion zt3019ea) and for few weeks now, has started to make this high pitched noise (like a mosquito!) only when connected to the charger. I replaced the charger with a new one.Same thing. Then that new charger (8 days-old) died yesterday. I thought I needed to get a new battery but at the same time is it really worth it for a 6 year-old laptop? (the hard drive has been replaced in March) Thanks for your help! Marine.