I have predator g9-592 with 6700HQ, GTX 980m and 16gb ram, the temperature was as usual around 60-75 degrees on heavy and long gaming sessions and on the normal usage or light usage the temperature reach 35 degrees, and an fps on games such as dishonored 2 AC syndicate, tomb raider 45-50 fps and on league of legends a solid 120 fps
before 2 months I had an issue with my motherboard and the laptop didn't start at all, went to warranty and they fixed it by replacing the motherboard, everything worked as it should but after couple of weeks I noticed that the laptop is getting fps drops in games that i used to run on 45fps and 50fps and it gives me 30 fps, then 10-25 fps no matter how i change the settings of the game, league of legends spikes between 50 and 80 fps also no matter on low or very high settings.
and then i noticed the temperature getting unusual numbers 95 and 96 degrees when i have almost nothing heavy open.
GPU temperature 85-87 degree
i'm afraid the GPU or CPU have been damaged because of the heat which is why the performance isn't normal.