I won´t recommend the GTX-1060 with 3 GB because they have less cuda-cores, a lower bandwidth memory interface and usually lower base/boost-clocks.
I have build a small rig with 2 GTX-1060-6:no case yet (gonna choose a cheap ATX Midtower with at least 3 120mm intake (!) fans)
460W PSU
ASRock B150M mainboard (space between the two PCI-E ist important)
2 x DDR4 4GB
120GB SSD
2 x KFA2 (Galaxy) GTX-1060-6 OC (non EX)
Win7_64
NHM v1.7.5.12

trimmed down to 230W from wall (= 1.44 EUR/day at 0.26 EUR/KWh)
... should ROI rel. fast even at my high power costs
