Pc randomly restarts

Hi everyone, My PC randomly restarts at odd times, not necessarily during heavy gaming. It has also restarted during internet surfing and youtube videos. Its a bit low end and some of the parts were bought used, but i really need to narrow it down.

Specs; I7-3770 16gb ddr3 512 hdd 128 ssd Rx 590 sapphire nitro + (used) 600W E-dragon psu (brand new)

I suspect it to be the power supply as it is some chinese company, but i did buy it brand new with warranty.