You know where and what the problem is, so fix it. Blow canned air to clear the fan and heatsink. Check then to see if the fan is still working at any time the temp climbs. If not, time to replace the HSF or just the fan.
So i download SpeedFan when my FPS's started to drop realy hard when i play games on Steam, and the temperatures when i am with skype and steam open are:
Core 0: 67C
Core 1: 67C
Core 2: 67C
Core 3: 68C
Intel(R) Core(TM) i7-3630QM CPU @ 2.40GHz
I have the laptop for almost 2 years, and this never happened.
The fan is not making any noise at all when i start a game, i think before it used to do...
When i start to play csgo, the temps go to 90C, all of them..
The pc has 2 graphic cards i think:
Intel HD Graphics 4000
NVIDIA Geforce GT 640M 2GB
When im playing csgo SpeedFan Shows:
Core 0: 85
Core 1: 88
Core 2: 86
Core 3: 84