I tried 1185 Mhz with 1.15V but it crashed again.
I'll try lowering the Mem. clock but if it solves the problem, VRAM is the issue. So I need to RMA the VGA Card.
Continue to test PC...
Prime95 blend, 20 minutes --> no error.
24 hours is overkill i think. A lot of people say "I pass 24 hours run without error but games are crashing in first 3-5 minutes."
I tried DX11 or below DX11 games already.
I even force Dirt3: Complete Edition to work with DX9 but no solution.
I tried reducing the VRAM frequency. (1960 instead of 200 Mhz.) --> Metro Last Light ran 20 minutes instead of 3-5 min.
I closed Last Light and ran Metro 2033 but it crashed again.
Today, I ran 3DMark Demo and PC crashed immediately.
I did a lot of test for hardware and tried a lot of suggestion about software.
I'm absolutely sure that my GPU is defective.
I'll RMA my graphics card. Thank you for all help. Much appreciated.
I'll write the results after RMA process.
Here is the result: I took my money back and bought ASUS Dual GTX 1060. Problem solved. GPU of my Strix graphics card was defective.
Don't judge me, there is no RX series graphics card because of the miners.