Now, the questions that I got for you:
Are the steps above correct?
My risers have 6-pin, Molex, and SATA power connectors at the same time to chose from. I heard connecting via 6-pin is preferable but can't recall why so.
Problem is, after I connect 4 GPU to the PSU, I won't have any free 6-pin connectors left.
So, what's the smartest of the two: to buy some 3rd party 6-pin cords and connect the risers via 6-pin slots, or to connect them via Molex/SATA official cords I received with my PSU?
either way if both handled properly by understanding its power handling of each cables then you sure safe with it, here is the guide for reference on each cables.
http://www.gpuminingresources.com/Thank you very much for the link!
However, I studied it and now I have one more question: how much power do I need to supply directly to the card via the 6-pin on its top and how much do I have to supply to the riser (via Molex, apparently)? Or is it just the combined power supply that counts, and the proportions don't mean nothing? That's not covered on the page you gave me, at least not directly.