My PC is having some odd issues

[SeamedCashew131]

My PC has been having some bad issues lately. It will randomly power cycle, when it is turned on. It sometimes takes 5 minutes to turn off then back on, and sometimes it takes 5 seconds. I am 100% sure it is a hardware issue because it did it with and without windows. I have already uninstalled windows and it still did this when trying to re-install. I went on to Youtube to try to find an answer and it said it should be a power supply issue. So, I borrowed my friend's extra power supply and the issue was still there. I also tested to see if it was the RAM while I could, and i borrowed an extra stick of ram, it did not help. All of my parts are brand new and out of the box. I was talking to my cousin, who owns a computer distributing company and has a degree in computer engineering, he said that it possibly could be a motherboard issue. So now I come here, has anyone ever had this issue and do you believe it could be a motherboard issue? Thanks.

 

(and some motherboard recommendations would be nice too)

 

My specs:

Ryzen 5 3600 CPU

GeForce GTX 1070

G.Skill Ripjaw 2x8, 3600 RAM

HP EX950 1TB ssd storage

HX1000W Corsair PSU

ASRock Phantom Gaming 4 b550 motherboard

Phantex Phantom eclipse P360A case