Best way to utilize power supplies for 6 GPU rig

[skaughtz]

New to mining and going to set up a rig using all of the GPUs I have in the computers throughout my home.  The rig will consist of:

 

1080 Ti

1080

2070

2060S

2060

2060

 

Asrock H61 Pro BTC

Pentium G2020T (35W TDP)

2 x 4GB DDR3 1600

 

I have three power supplies that I can use to power the rig.  A 750W Gold, 650W Gold, and 620W Bronze.  My plan as of now is to use the 750W to power the board, 1080Ti and 1080, then use the other two to power 2 of the remaining cards each (with the 650W gold powering the 2070 and 2060S and the 620W bronze powering the two 2060s).  The 750W has four pcie cables, but both the 1080Ti and 1080 are 2 x 8pin so I wanted each plug to have a dedicated cord.  Considering that I will likely be undervolting the cards, or at the very least limiting their power to 80%, can I split power between two supplies, or should I stick with my original plan and use one PSU to power 2 cards each?

 

I am getting inconsistent wattage totals online.  Whattomine, for example, suggests the cards will pull 870W.  The rest of the system, according to Outervision's power supply calculator will pull 121W.  So 991W total.  However, calculating everything with Outervision's power supply calculator estimates the total draw at 1567W... soooo any advice would be appreciated.  If I can get away with running only two power supplies I would prefer to simply because it is one less moving part that will be running 24/7.