Join Date: Mar 2011
Location: Still Breathing, United States
Discrete sound is overkill unless you're an audiophile.
The m2 is a luxury item, so if you're looking to limit cash, go with a SATA SSD. There is little real world gain over a cheaper SATA III SSD for most wirkloads (next to zero in games). Only get it if you're future proofing for heavy I/O loads.
Power supply is up to you. 1000 watts would be advisable for twin 7950's and a 1950X. If you seek the 7950's for a more efficient card, you could go down to 750-800W.
Given insane GPU prices, you can probably sell the 7950's for around 300 bucks and use that money towards a placeholder GTX 1050 non-ti. In 4-6 months 580's and 1070's may well become plentiful, and you'll maximize performance per dollar while GPUs from 2012 command a price premium.