Need help CPU / PSU

hi...

im not sure whats the problem is so i'll just tell what happened..


1st.
whenever i play a high 3d game ex:WOW / Call of duty
my PC hangs... cant ctrl alt del / alt tab / mouse wont move...
so i have to restart...

but i noticed whenever i face my aircon to the CPU
the CPU won't hang at all..

so maybe it's the video card ?.. but the display is just fine...

so i checked the web and pc tech help forums...

and i tought maybe it's the PSU...

i had a 300W PSU

so i borrowed a 350W PSU..
removed the 300W PSU and placed the 350W PSU

and yeah.. i play a game, and the CPU won't hang...

but for some reason.. while i was playing..
a loud spark came from the PSU...

so i got scared and unplugged the whole PC...
( there was no burnt odor thou.. )

actually it took me a lot of courage to turn this PC on again..

an right now.. i'm typing far from the PC...
i'm scared of being near when this PC blows..
so far the PSU havent sparked yet..

so.. help...
what's the problem..
what's wrong...

i really need help..

Use the old PSU. The 350W is worse than what you had before.
A bad power supply can destroy the whole computer.
As said above please list your hardware.