Okay, I think I'm having a similar issue here, but it isn't an idle situation. When I'm playing games everything will be fine, and then all of a sudden my computer shuts off. Its annoying because it only happens on a certain few games, and not everything I've played. Most notably and recently its happen on Evolve and Dead Space 3. I'm not sure if its a temperature related issue because I have no way of checking temps, and I have tried download coretemp, but everytime I start it up it freezes my computer, so that won't work. Also, I'm not even using stock cooler I'm using SilverStone Argon series AR06 low profile fan, and my system runs at around 72C the BIOS. I've reapplied thermal pasted once because I though the first time I applied might not have been good, and the temps still are at 72C. Not sure if this is normal, or if this is the problem.