Pc reboots randomly but doesn't turn on properly.

[Ranyleb]

I built a pc 1 month ago and this problem accured already like 3 times and i'm not really sure what's causing the problem. My pc would reboot randomly and then it doesn't turn back on. In fact, it's on but no fans running , only motherboard led are on but no post.
I don't understand please help me.
Specs:asus rog strix gtx 1070.
Intel core i7 6700k
msi z170a krait gaming m3

 

[Axle_V]

full specs if its possible also have you overclocked your CPU/GPU?

 

[ko888]

What's the brand and model of the power supply unit, SSD and/or HDD and memory?