Why doesn't the image display on the screen?

Question

Computers

System
Core 2 duo e8300
Asrock g31m-s
Ddr2 2x2 kingston kvr800d2n6
GTX 950 asus oc
aerocool vx plus 500w
2 train Western Digital
When the speaker was connected for the first time without RAM, it gave 3 signals saying that there was no RAM, it turned on the RAM, it was silent and then forever silent. I tried without a battery I tried with one die, the speaker does not say anything. There are no swollen capacitors, the bridges don’t burn either. The video card is 100% working, I went to a friend and checked it. One of the three percent of the mother or power supply burned out, how to understand what exactly I don’t know tomorrow I’ll check with another power supply and another mother at 775 I can't find. I also tried to run another platform, but the problem has not changed, everything is still spinning, but there is no image
How to find out what exactly is out of order?

Answer 1

Probability of failure:
PSU -60%, mother - 39%, RAM - 1%.

Answer 2

What was the problem?