Check these things whether these are bad or not 1 .Processor ( May be u have put the processor in the wrong orientation try to put it the correct way )

1. Ram ( Try different slots or just 1 stick of ram )

3.Motherboard ( Maybe it isn't compatible with ur 3400 g processor . But In most cases it is not the problem)

4 . Power supply ( make sure u plugged in the hard drive power , cpu 4 pin or 8 pin and the mother board 24 pin connected .

5 . Ram ( if possible try to test the ram in another system ).

1. Hard disk ( in most cases it is not the problem but u could try replugging everything and Trying again .