^ I still need the RAM part-number. Also, what exact PSU model installed. As much information as possible about you system is required to determine a cause.
Just reading partial info "flicker" it could be a bad PSU or partial short or a poorly mounted component, etc.
I need the PSU model to determine adequate power and number of rails, DDR P/N to determine compatibility, MOBO P/N - otherwise it is guessing behind a curtain.