Ok so I've read here and there that power supply buzzing is probably nothing to worry about, and am just wondering if the fact that it's a higher wattage than the original supply (90W as opposed to 65W) is the cause? If this is the case, then so far as I understand there's nothing to be worried about. But if there's, let me know!
The voltages match so that's no issue, and by the way, it's for a Lenovo T410 Thinkpad.
Added (1). Oh err the buzzing is very slight, you have to hold your ear close to hear it.