My PC reboots whenever i join a server

Put the summary of the bug you're having here

What I expected to happen was...:
it would happen once and then stop

What actually happened was...:
it keeps making my pc reboot

Steps to Reproduce:
1. launch minecraft
2. join a server (i play on the nexus and i play sg)
3 join an sg for example and after about instantly to 2 minutes your pc has rebooted