To settle it once and for all - Dual 8-pin or two separate PCI-E cables. : r/nvidia
Amazon.com: 16 AWG GPU VGA PCI-e 8Pin PCI Express Graphics Video Card GPU VGA 8 Pin Female to Dual GPU 8(6+2) Pin Male Splitter Power Sleeved Extension Cable 8 Pin GPU 12-inches
Amazon.com: PCI-e 8 Pin Male to Dual 8 Pin (6+2) Male PCI Express Power Adapter Cable for EVGA Modular Power Supply Cable for Graphics Video Card 8 pin Splitter 25+10 inches TeamProfitcom : Electronics
PCI Express Gen 5 Power Connector Leaks, Offers up to 600W - ExtremeTech