Yeah, as others have pointed out, that's not going to work.
1) 2x 750 PSU's are not enough for 8 1070 TI's. You can manage with 2x 850's.
2) You will have to put 4-4 GPU's on each PSU because I believe the G3 850 only has 4 GPU slots (therefore the 750 G3 will not have 5+).
If you don't already know this, you will need a Daisy Chain to link the PSU's to your mobo.
2 x 750 are PLENTY for 8 1070 ti cards running at EFFICIENT settings.
An 850 is enough for *5* of them at efficient settings with a fair bit of headroom.
The issue is a combination of 4 VGA + 4 SATA/Perph slots on the PS, NOT just the VGA slots (which have DUAL power cables avalable).
Yeah, you're right. 1x 1070 ti consumes 180 kw/h. 80% of 750 = 600 watts safe capacity. You can have 4x 1070ti's running on 80% TDP and you will be fine. My 1070 ti's run on 65% power and are very efficient.
