for sata/molex connector powering only one riser for low power GPU, like a 570/580. if connect more than one riser will be burn cable or connector(no matter what quality of PSU/Gold or Platin). Modular PSU not good for this job. tried with cooler master 1200w platin series too. For high power GPU's connecting direct 6 pin pci-e cable from PSU.
I have more than 5 years 2 raisers connected to 1 branch of the power supply. The raiser does not draw more than 75 watts. The only problem is the poor quality adapters that come with the raisers. I do not use them, but connect the power supply directly to the raiser.
I agree with you, but we can't find everytime good quality components or cables.