That's how I have it set up with a 1000w and 500w and 4 gpus only drawing about 750w at this time. I am thinking I just have some cheaper connecters mixed in there. Is there a good supplier that has quality and reliability?
you could just make your own cables lol, I make all of mine for my mining rigs as I needed special ones since I use server grade psu's and breakout boards, its even good for atx psu's too in case you need to replace a cable for some reason