you're feeding each 1080ti with 200w, this is a nobrainer.
You don't need over 70% power limit anyways, it makes little to no difference.
yes i totaly missed that you have only 1200w psu ...
stock tdp for 1080ti is 250w...if you have MSI its much more
edit: just buy another PSU for (like 800) for 3 cards and risers and the rest put on that 1200w .... you will need PSU with enough 8pins ofc

be careful when reading. @OP uses two PSUs to power a mining rig. I think it has no problem with power consumption or the like.
I connect Corsair HX1200 to motherboard,SSD, CPU, 3 riser and 3 GPU, and Gigabyte Xtreme Gaming 1200w to 3 riser and 3 GPU.