Computer restarting when playing Overwatch

[ninjajack]

Whenever I start up overwatch my computer restarts, I tried other games and it seems ok. It also restarted halfway through writing this post which was the first time it has done it out of a game. I ran a stress test on both my CPU and GPU and kept an eye on the temp, my computer didn't restart on either of the occasions I also ran a virus scan to eliminate that. Any other suggestions of what it is and how to fix it?(side note, my pc specs are:

Intel core i5 4690k

gtx970

corsair rm650i

cooler master Nepton 240m

corsair vengeance 2x8gb

nzxt h440

[vorticalbox]

any overclocks? if so remove them.

[ninjajack]

1 minute ago, vorticalbox said:

any overclocks? if so remove them.

Nah I haven't over locked anything, Ik I have a 4690k but when I bought it it was on sale and cheaper than the non k