The problem you described could be due to some reasons,most common are : Too high temperatures,Faulty Power Supply,Faulty Ram,Faulty GPU or Driver issues.

1) Download Speed Fan and check your temps while gaming
http://www.almico.com/speedfan.php
If you notice very high temperatures you should open your Pc clean all the dust off it and eventually reapply thermal paste on your CPU (Check if all the fans are spinning aswell)

2) Download and install Iobit Driver Booster and run it,see if you are facing the problem even after updating all the drivers.