Need tips on adding extra 6 pin PCIE outputs to a modular power supply

Hey everyone I’ve got a few modular and semi-modular PC power supplies, and I'm thinking about using them to power some S9 miners with two cards each. Most of these units are 1000W or more. Honestly, selling them wouldn’t bring much back, so it might be smarter to repurpose them for the S9s. I’d need a total of seven outputs for everything. I was thinking I could use one of the existing hardwired PCIE outputs (whether it’s 6 pin or not) for the control board. Then, for the dedicated high amp PCIE modular outputs, can I just solder on some connections and split the load, like two cards per output? I’ve only seen cables that go from x8 to x2, but couldn’t I just splice one and add another connection? If this works, I could set up a few more miners since they would be low power and quiet when running at 700/800W. Has anyone tried this or have any thoughts about it? I’d hate for these PSUs to just sit around doing nothing. Check out the pics I’ve attached. Thanks!

To be honest, modular plug PSU's all have 1 major problem: They are pushing the maximum current rating through the contacts and generally have only 18ga wires between the PSU and PCIe plugs. Ok, that's 2 major problems... That said, since you are talking about running at reduced power it may not be an issue, just periodically check to see how warm the PSU connectors get. Yes, I've had a few rather spectacularly fry over the years from when I used them to power s3's & s5's... Other thing to keep in mind is that particular PSU has 2 independent output rails. DO NOT connect power from the 2 different rails to 1 hash board! They will be shorted together and fight each other.

@NotFuzzyWarm Yes i will be running only 2 boards @ 700w or 800w. Is that why 'common rail' modular PSUs are so expensive? The only PSUs i can see that have enough outputs (X7) are the EVGA ones and they are silly money, i'm surprised that nobody has found a decent PSU and 'modded' them for more outputs tbh.....I just can't find makes that suffice apart from that brand? I think if i open it i can see rails and go from there, 3 on each for the hash boards and an existing 12v ouput for the control board. Thanks for the advice.

Looks like the +12v are seperate rails and GND/-12v shared. I will just add an extra pin to each double 8pin >x2 6pin. So i will have a set of two 8pin >x3 6 pins. Current will be approx 800/12=66.67a Is this correct? https://ibb.co/7bHRwJ2