Acer Aspire 571pg :: FPS Drops On Games - Overheating?

Recently i buyed a laptop (Acer Aspire 571 pg) this laptop is very good for browsing and watching videos, etc... I'm happy that it can handle those things perfectly But i have a big issue when i try to play some games.For example GTA IV. I start the game normally and after a couple of minutes the game stutters/ drops fps constantly. I mean... It runs well in the first 4-5 minutes, then it starts to run slow for a couple of seconds and then goes back to run normally for another couple of seconds, and then again the game runs slow, and this keeps going and going as long as i play.

Specs: [URL]... HDD: 1tbO.s: Windows 8.1 [It was originally Windows 8, but i updated the Os for free] (Maybe this was the problem?)RAM: 8gbVideo [1]: Integrated Intel HD Graphics 4000Video [2]: Dedicated Nvidia 710m [1gb] ddr3Processor: Intel i7 3537U 2.0ghz [2.5ghz in turbo]

So I really don't know what to do, this fps drops are really annoying. I've tried:

-Installing new video drivers [They're up to date]
-Installing new audio drivers [They're up to date too]
-Changing battery settings, doesn't make much difference in balanced mode or high performance
-Low the settings and resolution of the game [This keeps happening even on the lowest settings, it stutters/ it still gives me a fps drop]
-Defrag my hdd [Nothing changes]
-Updated my bios [The problem still persist]
-Turning off vertical sync and other various settings on the Nvidia control panel.

The thing is that i used Nvidia inspector just to check the gpu temperature and i notice that when the temperature reaches 60 to 70 celcius degrees the game starts to run slowly and stutter. I've this cooler connected to my lap: [URL] ... I've the same pad just in color black.But even with that thing connected the temperature still goes up. Maybe i need a better cooling pad? What should i do to get the fps stable?