I do agree with you but you mention you have 8gpu on 1000w is something I would like to learn from you. Do you mind sharing the cabling diagram or a pic would do.
I have a plat 1000w with 8 x 8pin but I am worried to push it.
There is nothing special about it, just connect everything together. Only thing, I am using gtx 1070 with lowered power limit, so they consume only 100-110W.
When you use 2 psU, the other one you just short the 2 pin to force it to power up? need any 5V load to have full 12V power?