All prices from newegg.com as of 06/05/2017
NVidia 1070 $400.00
1080TI $735.00
SSD (128gb) $60.00
windows 10 - $100.00
Ram (8gb) 50.00
PSU 1600W $350.00
CPU (2 core Celeron) 60.00
Mobo $150.00 (no set board, but 150.00 will get you a 7 slot)
I am not pricing risers, case, or connector needed for 2 psu’s
Bare bones (base) for mobo, cpu, HD, o/s, ram, and one 1600w psu is $770.00
All H/S’s rates come from this forum and bitcointalk
7x NVidia 1070 = $2800.00 + base = $3570.00
H/S for an O/C 1070 is 450ish x 7gpu = 3150 H/S
TDP roughly 150w per card x7 gpu = 1050w + mobo 100w = 1150w
Summary: one PSU needed, cost $3570.00 getting 3150 H/S
7x NVidia 1080 TI = $5145.00 + base = $5915.00
H/S for an O/C 1080 TI is 750ish x 7gpu = 5250 H/S’s
TDP is roughly 286w x 7 gpu = 2002w + mobo 100w = 2152w
Add seconds PSU $350.00
Summary: 2 PSU’s needed at a total cost of $6,265 getting 5,250 H/S
The price difference between the two system $6,265.00.00 - $3,570.00 = $2,695.00
Take that $2,695.00 and you can make a 4 GPU rig getting 1800 H/S, + 3150 H/S (from original 1070 rig) = 4950 H/S’s
Based on numbers from 06/05/2017 you should get 300H/S more from a 7 GPU 1080 TI rig spending $6,265.00 compared to 2 NVidia 1070 rigs with 11 GPU’s costing the same $6,265.00
** 3 additional 1070 GPU’s can be added to the second rig for only the price of the GPU’s giving an additional 1,350 H/S’s; for this exercise though that cost exceeds the base cost of a 7 GPU 1080 TI rig