Say what? How on earth do you come to that conclusion? Lets see your math. Ill show you mine right now.

Rig with 12 1070Ti's at 150 TDP each. (No overclock or TDP adjustments) https://www.buriedone.com/hashrates

6 1070 TI's per PSU= 6x150w=900w

PSU1= 900w
PSU2=900 + CPU/Motherboard/SATA 200w= 1100w

and each of his PSU's are rated for 1300w

I would still give them a 65% TDP Overclock  +150 clock/+500 memory and the power usage will go even lower. https://www.buriedone.com/tuning

Problems are probably a combination of BIOS setting and/or update AND/OR Driver issues during install.  Go into device manager and click on view tab then show hidden devices and have a look at the mess under Display Adapters and Sound and Video Controllers.

DDU to remove it all and disconnect all GPU's.  Install one at a time and reboot after drivers install for each GPU.  Boot back up and verify GPU installed successfully.  Then and only then shut down and install next GPU. Repeat cycle until all are installed.