I've had this laptop (Samsung NP700z7c-S01UK - for reference) for a couple of months now, but it has only just developed this problem. The problem does not persist under regular non-gaming use. While playing games that seem to require a heavier load than usual, the machine simply shuts off, no BSOD, no warning, it just cuts out. Almost like power would cut out if it were fusing.
I haven't changed any drivers or as far as I can remember any software that would affect this kind of issue, so I'm stumped.
I have downloaded Intel Extreme Tuning and done extended stress tests on the graphics, CPU, and memory (separately, it won't let you do them simultaneously), without issue. So I'm assuming the issue is something to do with power. I'm guessing maybe it is not being supplied with enough power when the system is under load (this review seems to say this too - http://www.notebookcheck.net/Review-Samsung-Series-7-Chronos-700Z7C-Notebook.76839.0.html). The power adapter is 90W, and during the stress tests I saw the CPU go up to 38W at peak, and the memory was about 32W at peak, then adding the GPU to this, it is getting on for the 90W maximum, not including the screen and everything else!
The laptop does seem to get warm, but not excessively so. It feels and sounds like it is coping very well with the load! The frame-rate in-game is also consistent.
EDIT: So after extensive testing - I tried to play the game not connected to the power adapter and it played fine for the duration of the 80% charge of the battery, then when I plugged it in and tried again it cut out after a few minutes.
From deduction I think the problem is power related, so I am going to purchase a 120W adapter and see if the problem resolves itself and turns out to be simply a case of not getting enough current to charge the battery/keep it charged and run all the hardware sufficiently.