windows 7 random restarts or powers off without warning

[Will_85]

hi, im new, but i wondered if i can pick brains a little. My Friends computer who round like daily, started to have odd random restarts {this was the first board Asrock n68s amd dual core) we then swapped the mobo for an upgrade (msi 990fxa gamin athlon II x4 620) which after fresh windows install powered off abruptly. and this would become more frequent as we tried to diagnose / solve the issue. hardware is about same apart from swapping cpus to rule out errors. same corsair 2x2gb sticks and same graphics card, im hearing possible PSU symptom. (we have also tried a third mobo (asrock 990fx extreme3) which also devolped random restarts after windows was installed and just about got to a usable state. any ideas? please...

 

[rocktalkrock]

If there is no pattern to when the computer restarts and there is no blue screen of death, just shutting off suddenly, that sounds like a faulty power supply. How old is the PSU?

 

[Will_85]

thanks for reply rocktalkrock, no, their dosnt seem to be any pattern to it, no hint of a BSOD. the psu is fairly new barely 2 months usage (corsair vs650)

 

[rocktalkrock]

thanks for reply rocktalkrock, no, their dosnt seem to be any pattern to it, no hint of a BSOD. the psu is fairly new barely 2 months usage (corsair vs650)

Did the problems appear when he first started using the power supply, or did it work well for some time?

 

[smorizio]

can be two issues. one the mb are shutting down to keep the cpu from melting if the coolers not on right or the paste is gone bad. have you botted into the bios and watched if the cpu temps climb and the mb shuts off or see in the bios if the power supply rails out of atx spec. to see if you have a power issue see if someone has a volt meter connect the black probe to any of the black ground wires on the 24 pin atx cable. on the red lead look for the 3.3 12v and 5v rails. run the pc and watch the meter see if any of those rails drop.