New PC randomly reboots

[UnForsaken Void]

I have recently put together a new pc that includes:
Ryzen 5 5600x
Asus b550-F gaming wifi
G.SKILL Ripjaws V Series DDR4 3600MHz 32GB
Corsair RM850x
Asus Tuf RTX 3080
Kingston 1TB nvme ssd
a Seagate HDD

cruical 500 GB 2.5' ssd

For the past 3 or so weeks it has been in and out of Canada Computers with them trying to find out the problem. They have already made me change the PSU from a RM750 to the RM850x believing that to be the problem. The motherboard has been replaced with a new one thinking that the old one was faulty. I'm also currently debating to RMA the CPU back to newegg to find out if that is the problem. the only thing in the system that hasn't been changed is the Ram and CPU at this point and im slowing lossing my mind because of this. The PC can turn on and run, sometimes for a few hours without issue until it power cycles and goes back to login. Other times it power cycles within 20 minutes of use. for a normal use case of my PC i usually have a game open with a twitch stream on one screen with discord on another for a total of powering 3 screens. this setup worked with my old build that only used a 750w PSU. Any help or advice with this depressing problem would be greatly appreciated.