Samsung Laptop going into standby mode without warning

So over the last few days, my Samsung laptop has been putting itself into standby mode without any warning. And I for the life of me cannot figure out why.

All options to turn off the computer have been set to never while it's plugged in, so it's not that. I suspected it was the laptop overheating for awhile, but I've got SpeedFan running and with the latest shut down the core temperatures were only around 55 degrees Celsius. I've seen it run up to 70 degrees when I really pushed it to investigate how hot it got, and that didn't prompt any response at all, except for the fan speeding up, and the laptop cooled down pretty fast when I let up on what I was doing.

Is there any other reason the laptop would shut down like this? I'm not the most computer smart in the world when it comes to the internal workings, so any help would be appreciated.

Potentially relevant things:
Samsung laptop NP350V5C
Radeon graphics card
Intel core i7
Windows 8 OS
 
Back