This is not quite an answer, but I wanted to share my current experience and maybe it'll help others like you. I have the PH517-61-R0GX version and same thing... GPU fan noise went crazy and sounded like a blade fell off inside. I opened it up and there's ZERO damage. I used the included fan control software interface on the laptop and slowed down the fan... it registers it at 300 RPM and the noise is very minor, but as soon as it ramps beyond that, the noise is terrible. (this thing is always hot so it's required.) I ran it open and the noise was still present to confirm nothing was pushing on the fan housing. I performed a deep clean too, it only slightly helped. The next thing I can think of is to either: (1) Replace the fan entirely which they don't make anymore. or (2) Open the fan housing and inspect for problems... maybe the propeller is unbalanced like a few people suspected. idk if I can fix that... or maybe lint it stuck in it? or (3) I replace the propeller and hope that works. But I don't know...