I did a small water cooling build in a V351 a couple of years ago (no were near as nice and detailed as yours) and found the PSU's to keep dying due to being the only source of heat extraction in the case.
Even with my cpu and gfx water cooled the motherboard temps were very high to lack of airflow in the case which would result in PSU's running at mega fan speed and blowing up im guessing because they didn't like the constant heat.
What are you mobo temps like do you have decent airflow over it? Maybe a design flaw i overlooked when building my rig.