Need help with pc randomly restarting.

[melanismdragon]

So here is my spec, 

core i7 8700k, cooler master air cooler

32 GB Z-trident RGB ram

gigabyte z390UD motherboard

ASUS GTX 1080ti

Corsair CX 750M modular PSU

WD 500GB NVME SSD, WD 500GB 2.5in SSD, 1TB hard drive

 

(motherboard, PSU, cooler, case, ram all brand new)

 

So here is my problem, the pc would randomly restart, usually when its idling, but sometimes games would make it restart too, for one, when I get into the training mode loading screen of COD warzone, it would restart. So after I know when it will restart, I looked at my motherboard, and to the bottom right there are four leds indicating cpu/dram/gpu/boot, in the owner manual it says its the status leds. so when the pc restarts, the cpu led would flash once, then it cycles through the 4 leds as its starting.(the cycle might be normal start thing), I have a video of that. some guesses I have is if there is a short somewhere? or cpu/motherboard has a problem, but it works alright normally, or the drivers, bios? I want to ask here first before I update my bios etc.

 

Thank you!!