First thing you should check the voltage coming from the PSU unit to see if it's sending the correct current.
Have you added each component wattage usage against The PSU you have. I recommend to use up to 80% capacity.
I would recommend that you try each RAM stick Individually one at time, then try reseating the GPU and replacing if possible to see if that is the issue
After that I recommend to test out each part individually like the psu. Last resort would to test out the mother board.
Try this site