Restart with steam games

Thank you for your help in advance'

Every time I load a game via steam my computer restarts. I've tried
starting these games in steam offline line mode and they work fine but not
in online mode.

Alext3

 

Have you done any updates on steam as they was a problem update which caused the problem. have you checked to see if you are not running steam as a administrator as this can cause problems too.

also have you tried uninstalling and then reinstalling steam to see if that solves the problem.

 

Ran the Belarc can't attach the Htlm


Cleaned the inside of computer, ran Avira virus and found nothing, Ran Glary,
undated video drivers, not sure if I am running steam as admin.

Tried to attach the htlm from Belarc, it said it was an invalid file.

 

Windows 8.1 64 bit build (9600) Lenovo 4th gen i5 12gig ram GTX 650 fresh intsall of drivers on graphics card, also checked to see if there were new drivers for soundcard Realtek. - tried clean install of steam - ran Belarc as admin and never asked me how I would like the report to be loaded

 

I should also mention that when I play the steam games in offline mode they
run without restarting.

 

Downloaded HWMonitor and Cpu core temps never get above 50 C and the GPU never gets above 55 C

 

computer restarted when i was playing in offline mode also. Is there a way to test my power supply?