Designed for next-generation graphics cards, schematics of the power connector show that it will allow up to 600W of power to be delivered directly to the GPUs.
As such, there would be demand for a new power connector and that's where the 12V High-Power Connector that is designed specifically in conjunction with the PCIe 5.0 interface comes in.You can see that the connector is rated for 600W power delivery and is PCIe Gen 5.0 compatible & not designed for legacy PCIe Gen 2 or Gen 3 cards.
The 12VHPWR connector is not designed to mate with legacy PCI Express 2x3 and 2x4 12V Auxiliary Power connectors.