The issue is with the pico PSU, but I'll get to that just after some quick background..
This is an HTPC build, primarily to play 4k content and specifically aiming for 4k/60Hz capability.
Parts are:
APU/mobo as above
8Gb 2666Mhz today, 3200Mhz arrives tomorrow.
Samsung 960 Evo M.2
DC-DC...