pc suddenly turn of without any warning

[mohsin69]

My pc turn of suddenly whenever i play vedio, transfer data betweeb usb and pc,etc any work. some times it turns of and led beside the reset button turn on and i have to unplug the cable from back wait and plug it again , sometimes it turns of but cpu's fan and lights of lan turns on. I've tried to reinstall my windows but when i try to install windows it also shut down or restart at expanding point. i've swaped ram, tried with on stick of ram, removing the battery from mobo, i'm not understanding what to do?
my pc config:
AMD athlon x2 64 2.5ghz
MSI k9agm2 motherboard
ram 2stick of 1gb=2gb
ATI readon hd 4550
400w power supply

 

[rds1220]

This is going to sound dumb but check the obvious first, make sure the plug is connected nice and tight to both the PSU and outlet. If everything is ok with that then download CoreTemp and see what your temperatures are your computer might be overheating.

 

[rds1220]

Also what is your PSU make and model. If the PSU is crap or if it is starting to die it could be causing problems.

 

[mohsin69]

Also what is your PSU make and model. If the PSU is crap or if it is starting to die it could be causing problems.

i've tried with core temp the overheat is not a problem .
and my psu is new 400wat .