Oh and my specs are
Motherboard: ASUS Z77-A
CPU: Intel Core i5-3570K 3.40 GHz
RAM: Kingston HyperX Fury Black 8GB DDR3 1866MHz
HDD:Western Digital Blue 1TB
GPU: MSI R9 270 GAMING 2GB
Mechanic: ASUS DRW-24F1ST černá
PSU: FSP Fortron FSP500-60GHN 500W
OS: Windows 7 Home Premium upgraded to W10
Hello
I have experienced this problem for the first time like 2 months ago. Sometimes when I work on my PC it out of nowhere says Turning Off, then It turns off and turns on for like 2 seconds and immediately shuts down repeatedly. I have to turn off the power supply button and let it be for some time ( maybe like 1-2 hours) and then It works normally like nothing happened. This does not happen everyday, it happens maybe like once per two weeks. Also sometimes when I wake up in the morning the PC turned on by itself while I was sleeping. Thank you in advance for all your help and answers and excuse my english please, I am not a native english speaker.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic