I've checked and this is NOT heat related.
Case: Zalman Z9 Plus (Temperature gage and fan controller)
GPU: MSI GTX 770 TwinFrozr IV 2GB (2 cooling fans)
CPU: Intel Haswell Core i5-4670k 4 core CPU running at 3.4GHz
CPU Cooler: Xigmatek Dark Knight SD1283 Night Hawk Edition
Motherboard: Gigabyte z87-hd3
This doesn't occur while playing BF3 on COMPLETE ultra settings, and not even on Mount and Blade Warband but occasionally my PC Shuts down without warning, no log off screen, just straight off. I really need some help!