Hey guys,
First post here, my 2013 328i, 90k miles (N26) is making a strange whine noise, sounding exactly the same as the video posted below.

https://www.youtube.com/watch?v=BY6GL4X03M4

I apologize if this has been answered before, just trying to properly identify the issue before the dealer costs me an arm and a leg to do prospective repairs as they have asked $4,200 to do a timing chain repair and even then said they could not determine if its the chain or the turbo. I've had people tell me it could also be the alternator or bad bearings. Dont want to see my baby crap out on me while driving it. Any help is appreciated.
Thanks!