I Have some Tempereture problem. Please Help!

[FrostX]

Those are my Computer Specs:
Gigabyte GA-K8NXP MotherBoard
AMD Athlon-64 +2800
512DDR 2700
Nvidia 6200 XFX VGA Card
Western Digital 80GB IDE HDD

The problem: I recently got a new 500Watt PSU, I had a problem in the MB, it didn't start it seemed I had to juice it a little bit. but now its working fine but when I start some games it flashes and freezes. I have to minimize the game and maximize it again to work again.
Note: this problem only occurs when the GPU Temp. gets above 50-55 Celcius.

 

[aman501]

To make sure its the GPU temp try removing the side of your case and blowing a fan on the graphics card to keep it cooler. Then, if it works you know you need to invest in a VGA cooler.

 

[FrostX]

Yes, I already tried that, infact I have added about three fans to the chassis, and started the game with opened cover, the same problem occured but after more time, I know the GPU Temp. from the Nvidia Settings.
I tried this VGA in another computer and the problem didn't occur, can this problem have to do something with the Motherboard and the PSU?