Overheating and FPS drops on Dell G5 15 Gaming (5587) during games

Hi,

I am looking for an advice about my Dell G5 15 Gaming 5587. Laptop is overheating (mainly in the spot between screen and f1-12 buttons) during games (World of Tanks, CSGO). I guess this overheating leads to drops of fps from 100-120 to aprox. 50 fps for a minute or so. Is there anything to fix it or should I try to return the laptop to the seller, I have it for a year now. Buying a cooling pad didnt help a bit. 

Thank you so much