I guess you are attempting to get into UHD 4K gaming so that will get you 40 to 60 FPS on the usual UHD 4K monitor.
I'm finding folk that try this get really bummed and burned out about that. I really suggest looking at a single 1080 Ti then the 2K gaming monitors. Much better results and great pixels.
As to the PSU I think you are shopping the 1000 Watt PSUs in that rig due to the dual 1080's.
So if i were to build this pc...https://pcpartpicker.com/list/fDRwpG what would my power supply be? i dont know much about how to determine what it should be also some tips so i can determine what the power supply should be would be good too. thanks for your time.
EDIT: forgot to mention if this can be useful information, Im going to be game streaming on this pc aswell and give good quality streams to my viewers

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