Question Computer power crashes in FPS intensive mid to high graphic detail games

Feb 22, 2019
Hello. before i start detailing the problem here are my PC specs:

CPU: i7 6700k (oc to 4Mhz)
Liquid cooling to cpu: Corsair H110i
Mobo: Gigabyte Z170X-Gaming 3
RAM: 16GB DDR4 Corsair vengeance (at 1066 Mhz)
GPU: Gigabyte "windforce" GTX 980ti
PSU: Corsair CX750M
PC is 2-3 years old.

About a month ago my computer started crashing in a manner as if you completely pulled the electricity plug from it and then returned it to power. it shut down completely (like turned-off, not restart) then after a second turned itself back on and restarted back to desktop.
It ONLY happen when i play games with high and sometimes even medium graphic settings on games like ME: Andromeda; Ace Combat 7 - Skies Unknown; even TW: shogun 2 on ultra settings does that.
I came to realize it happens only when there are FPS intensive moments (even a little) in the game when it crashes - regularly now. (for example, a lot of explosions or many things on the screen in high graphic environment). At low settings on all games it doesnt do it, if at all (maybe after a few good hours of gaming but not even always). So every time the graphics are up, there it crashes like that.

looking at my Corsair LINK as well as HWMonitor i didnt see anything out of the ordinary, though not having the knowledge on what to look for i might have missed it.
I suspect the GPU or the PSU. Though it might as well be the mobo or cpu...

i turned off auto restart option.
I clean and dust every part in the machine very well. all very clean.

Hope i described it well enough.
Please help!