The problem as I see it, and why i am still searching for risers that have a ground connected, is what happens when you use two psu's? (one psu with risers should have no problems at all, however watch what you are pulling on the molex lines.)

I use two psu's one seasonc 250 watt (22 amps on the 12v - and can happily pull 300-340, auto shuts down around 360watts) and a 750 seasonic as the power for the gpu's (4x6950 shader unlocked, 1.1v)

Using a motherboard with 4 16x slots, I didnt need powered risers for the 5830's but the 6950's need them after 3 cards (even with full slots) - anyway, my worry is that I am adding power from the 750 seasonic, and this gets grounded through the slot, into the 250 watt psu... This is obviously very bad. I havent risked it to see what happens, i need all my psu's so risers with ground are the only option.

 I think I am going to manually go through the ground pins and see which ones are grounding the 12v lines - then add this to the molex.

This should stop any issues...