Needing help

[NicholasRG]

I built a pc It ran fine for a couple months, then started randomly shutting off.  I've let it sit for a while and will boot into windows and run fine then shut off again after about 30 minutes. Sometimes it won't power on others it will run for a few minutes, shut off.  Specs are:

Asus rog strix b550-a (new)

Ryzen 5 5600g (new)

Rog strix rx 580

1 16gb corsair vengeance ram

Segotep 650 watt fully modular psu (1 yr) 

I have torn it apart, and tried just the MB and a dell 300w psu I had laying around and still does the same.  The Dell psu only has 1 4pin cpu plug.

[Bdavis]

Sounds like power supply or motherboard to me.