Computer freezes when playing games

Here's the thing, when I play games on the computer, after a few minutes until it freezes and becomes a buzzing sound, requires restart.
I've tried everything, graphics measure temperature, core, changing RAM slots, install the drivers, Direct X changed, still nothing. Hard disk has changed, changed RAM. Nothing yet.
I bought a new graphics NVIDIA GTX 460, and put a new power supply from the 550w Does anyone have a solution or to change the motherboard, everything but the game works!?

do you that much like the game ??

anyhow , check the game in different systems and if the same occures , it may be the game ? DVD problem ?

and if it works in other systems , that says the problem is in ur device ...

it may be the RAM , how much RAM do you have ? and what is your windows ? 64 or 32 ?
and how much min RAM the game requires ?

I have 2 GB of RAM. The problem is not just one game, but in all. From weakest to strongest. 64. Thanks for the replay.

i think 2 gb is less if your system is 64bit