Computer randomly shuts down while playing games.

I have this Acer Aspire 5755G and I installed Windows 8 in it. When my OS was installed I wanted to play some games. So I installed Steam to be entartained. However, whenever I try to play a game and I am playing hapily, it can randomly shut down my entire computer. This is really annoying especially when I am feeling comfortable and thinking that it will not happen. This problem was also occuring when I was running Windows 7 and that's the reason I installed Windows 8, to see if the problem got fixed.
I don't know what to do so this is the reason I am in the forums asking.
One more thing, ERecovery won't work because PQSERVICE is not in my disk after installing Windows 8.
Thanks for your time if you reached this part after reading everything.

Sounds like your Laptop s overheating which might be why your machine shuts down all of a sudden.

If you can play the game with a decent Frames per second then all of sudden it shuts down.

Couple of ways to solve it is buy a cooling fan for your laptop.

The major thing is to get a air duster and blow the dust out. Laptops are more sensitive to dust which causes it to overheat.

Also download Speedfan to get Temperature readings of your CPU and GPU to find out.

this is a classic symptom of the system overheating.

the only thing you can really do is find instructions for your laptop and how to clean out the heatsink and fan. since you're going to have to open the notebook in order to clean the heat sink, you can try cleaning off the thermal paste/pad and use a better thermal paste. remember that more thermal paste is not necessarily better. this is not peanut butter. the thermal paste is only intended to fill the microscopic valleys of the rough surface so that heat conduction is better. thin is good. thick can lead to more heat.