Fix to this overheating of GPU

So I was playing a little MW2 and i was surprised i could run it at 120 fps, bad thing is my GPU heated up to 83 degrees Celsius! it started showing green patches on the game textures, which meant it was overheating.

so please help me now, how can i get my gpu to not overheat?

btw, my gpu is Geforce GTS 250