help me with this

my current specs: cpu: i5 3570 @3.40Ghz ram, : ddr3 hyperx fury 1886Mhz, Gpu: Geforce GTX 1050 ti OC edition ,psu: 350w I mainly play fortnite and some good grahics game like gta 5, forza horizon , pubg pc etc , but from sometime idk why the cpy goes up to 91 degree c* didnt do anything that...