I have a Dell Inspiron n5040 laptop from mid 2011 and i noticed that when the laptop is running off of battery, there is a squealing sound that seems to be coming from somewhere under the keyboard. I have an SSD so I've ruled out that it could be the hard drive and i know it also isn't coming from the speakers. I'm really stumped. Any help would be appreciated. Oh and one more detail I think I should add; it only seems to happen of I am transferring files over the network. So maybe faulty LAN Card?