My Computer Shuts Down While Gaming

Hello,

So i built a rig that i thought was to optimal standards.It has a i5 #4750 processor. 32 gigs of ram a evga gforce gtx 560 ti 448 core video card with a cpu water cooler it is the h80i model. i also have a solid state drive running the operating system and 2 raid level 1 1tb drives . and all this is sitting on a z87 gryphon mother board by asus with the thermal armor installed.And it is being powered by a 800watt psu .i had this problem on my old rig as well that's why i upgraded.now the problem is that im still having the same problem as in 15 minutes into playing high definition games like skyrim or deadspace it just shuts down and says that the computer shutdown because of a power surge my lights do not go off or was it raining and it sits right under a ac vent so the cpu stays at a constant 30 to 25 temp.any ideas?

Thanks For Your Help Guys In Advanced