Radeon 9800 pro, power supplies broke

[enrique85]

Hi, I just wanted to know is anyone could help me, I'm kind of scared.

 

The thing is I had this computer AMD Athlon 2800+, 768 ram, a7v600x asus mobo, 80 gb hdd and gforce fx 5200. It had no problem, but i wanted a better video card, so I bought a radeon 9800 pro, I instaled and the pc started working perfect, I used it for almost 24 hours without gaming much, I just entered the games to see the difference but didn't play more than a couple minutes because i didn't have the time. I saw all the radeon demos and everything was ok, but then when i started playing NFSU2 about 10 minutes into the game the computer turned off and the power supply got broken, it said 420 w, then i replaced it with a 400w that i had and started up ok, and worked well when i wasn't doing anything that required video card, but as soon as i opened the radeon demo it broken also, what could that be?

 

Thanks a lot for your help