At first, I need to say your rig is complete mess.
It means when some connectors passing to each other, it doesn't mean you can connect them together.
Just one question at start, did you tried to power up rig with only two cards?



Have you tried to do this with both psus? To ensure both psus are working?
This is main and basic thing to know. If so, you can continue further.
I was running similar setup 4x r9 280x with two corsairs 750W and 650W connected through add2psu.
Previously it was working with shorted green-black too. This setup was working for me even without powered risers.
And it wasn't necessary to hang some hdd, or dvd-rom to second psu, it was working without that.
So, in your case, I would do this. Unplug all those reduction molex/8pin cables which are powering gpus.
Then straight connect you gpus with 6+2 pcie cables, and I mean plug both sockets to gpu. That cable is builded for that.
I would connect 2gpus per psu for balanced consumption and best efficiency. 860 mobo+gpus+hdd, 760 gpus.
Then unplug that reduction sata/molex which is comming from first psu to add2psu.
Connect this through straight with molex connector, connect it with closer molex.
For power up risers, now you can use those sata/molex reductions, if you don't have enough molexes.
Same in here connect it with closer connector possible. Don't worry you can connect one hdd from one riser.
Connect gpus and risers from same psus. Then turn second psu on, then first on. Press power button,
and if all of your hardware isn't faulty, it should run now. But as you stated before, you said,
that you burned something, it means even if you have proper cabling now, it's not guaranteed it will work.
So try this, and I hope it will help.