When I plug my Oculus Rift in my computer, I can use it for like 5 minutes before my computer reboots.
I tried to repair the Oculus app using the setup, then I could play a 30 minutes session without problem. However, at the moment I unplugged the Rift, the computer went to another reboot, and the first problem reappeard.
I got the headset one month ago and I never had any problem during this period. I have everything up to date (Windows 10/Nvidia drivers).
I use a Intel core i7-6700 with a Geforce GTX 970, 12GB of ram and a 1TB SSHD disk.