So i got a new penovo legion 5 in the summer and now i constantly hear this sound. It stops sometimes but I don’t know what triggered it. The laptop is new and i don’t know of any damage that the laptop might have suffered. I can’t attach a video but its like a vrrrum, and it gets louder after a while. As I’m writing this it stopped, but I don’t think the fan stopped or anything. Also the laptop vibrates when i hear that sound. It’s on the right side of the laptop.
The only moving parts on that laptop are the fans. It looks like there are two fans, one on each side. Best guess without hearing a recording of the sound is that there is something making contact with the fan on the right, or a failing bearing. The laptop will need to exhaust more heat after it has been on for a while or under load, which would make sense why it gets louder with time. Considering that it is only 3 months old it probably is still under warranty. If so, I would use it to get it repaired.