You can look into the resources posted by @FarmerPling2 re: likely power consumption of those drives. The Dual Xeon is something you can look into via Intel.
@jgreco would likely counsel a higher capacity power supply, however, as he prefers a lot of margin, especially during spin-up, when power demands are higher than during idle times.
For my 8-drive array, the power consumption ranged from about 86-126W for idle vs. startup. These days, my NAS is consuming over 100W on account of the three SSDs I've added for the coming TrueNAS special vDEV (partitioned for metadata vs. small files). The drives are now ready, but TrueNAS not quite yet!
I would think long and hard about a dual-CPU setup unless your use case really demands it. A single CPU will likely serve you just as well in a storage-only scenario as SMB is single-threaded (AFP also) and hence CPU speed may have a bigger impact than the number of threads it can handle. I don't transcode, etc. so my CPU has yet to break 20% utilization on a continual basis.
On the other hand, VMs may trigger the need for more CPU cores but I'd support those with mirrored SSDs not spinners. I'm, very happy with my embedded motherboard that can handle 20 SATA drives natively, of which 2 are SATADOM for the mirrored boot pool. Add a PCIe HBA, and this system can easily handle 36 drives, features dual on-board 10GbE SFP+, dual 1G, a PCI 3.0x4 slot for a SLOG, a m.2 slot for a mSATA (I use it for L2Arc), lots of RAM, a dedicated IPMI interface, etc. The two PCIe 3.0x8 slots allow future expansion or NVMe addition.
