Hi guys!
I have some PC problem.

My pc random restart while gaming or rendering. It worked a lot but about a month the pc restarted while i gaming.
Causes by Psu or VGA ???

MY specs:
Motherboard: Asrock 970 Pro3 R2.0
CPU: AMD FX-6300
VGA: Gigabyte GTX 660 OC 2 GB
PSU: Chieftec 500w ctg-500-80p
RAM: 2*4 GB KINGSTON 4GB HyperX Blu DDR3 1600MHz CL9

So anyone can help??

I hope it will be the psu not other components....

Hey bro there's many factors that cause this here are some from experience.

1. might be processor (cpu) overheating
2. Thermal paste needs to be added and heatsinnk cleaned.
3. Ram might be over capacity specially if gaming

My best advise would be to check your cooling system like fan for dust removal or just replacing the thermal compound/paste. sometimes when your pc operates at 60 degrees or above it tends to lag. AMD will definitely restart as for intel it slows down as its a way to preserve your cpu.

Hope this helps. btw use cpu-Z to monitor cpu performance and temperature

Cpu : about max 50°C at gaming (With Speedfan) Arctic MX-4 with pasta ....

Try running mdsched.exe, see what comes up + try http://www.memtest.org/

Here the test:
http://kephost.com/images/2016/02/07/heatwave.jpg
and try some other test that you said Brian...

( I am Really mad that ******* pc...)

No memory fault with mdsched.exe.

Anyone has another idea???? Please....

do you have liquid cooling by any chance?

edit: if not what fans do you have and how many? in every directions. maybe airflow is bad and your chipset overheats.

No its not liquid....
Its LC Power Cosmo Cool LC-CC-95 with Arctic MX-4 on the processor.