At least for the layouts listed here: https://pc-mods.com/blogs/psu-pinout-repository https://pc-mods.com/blogs/psu-pinout-repository The motherboard cables do

At least for the layouts listed here: https://pc-mods.com/blogs/psu-pinout-repository https://pc-mods.com/blogs/psu-pinout-repository The motherboard cables do all kinds of different scary crossovers so never separate them, though you'll probably never have an "extra" motherboard cable in the first place. None of the other cables bridge pins on the PSU side, they "just" scramble the pins they're attached to at the other end.