Hi newcomer and welcome to the Tom's hardware forum.
U can use non-ecc unbuffered without problems but Intel don't recommend use that RAM type because when u work with server u always try to avoid errors in the data processing and for that the ecc RAM is very special.
Like u say that u don't want use it for critical task the non-ecc is enough because the ecc RAM is more expensive.
For the PSU all depends of the components that u want install with the mobo and CPU. RAID? Network card?.