Question System keeps randomly crashing

[Wattisforpower]

I use my system daily and nearly everyday this occurs.
I am using my computer normally until suddenly the screen blacks out and the sound sometimes buzzes, the computer fans are still running for about 30 seconds and then the computer reboots. Does anyone know what is wrong or how to fix it.
This is my computer specs:
Athlon x4 845 quad core processor @3.5GHz
16GB DDR3 dual channel @ 664.8 Mhz
ASUS A68HM-PLUS (FM2+)
AMD SAPPHIRE Radeon R9 390
Samsung Evo 500GB SSD
Seagate 2TB HDD
EVGA 600W PSU

 

[Dark Lord of Tech]

Good chance it's the poor power supply.

 

[Wattisforpower]

Good chance it's the poor power supply.

Oh, it's power rating is only 458W, so it should be fine, or is it the maker that is not very good?

 

[Dark Lord of Tech]

It's made by HEC and it's not very good.