Fudzilla posted PCI-Express 4.0 slot won't deliver 300W of power
A quote from the article:
It appears that earlier information regarding PCI-Express 4.0 slot and its ability to deliver 300W via slot was somewhat wrong as PCI-SIG has clarified that 300W were only fo certification process but that the maximum power delivery would stick to 75W.PCI-Express 4.0 slot won't deliver 300W of power @ Fudzilla