We were watching a movie on Plex and my computer, restarted after about 3 minutes. Powered off, started to reboot then shut down and rebooted all the way. Weird. Restarted the movie. Watched for a couple minutes then repeated the same process. Triggered on and off about half a dozen times within 20 seconds. So I unplugged it. Never had any issues before. Where should I start first? Power supply is Seasonic Focus Gold 850 watt.