Ok, i think you've got one wrong.
I have a corsair HX520 and it comes with 2x6 pin connectors, no add on to make them 8 and no 8 pin connectors.
I've double cheacked the cables that came with it that i'm not using it and it's defenetly not got anything.
Looking at the info page on scan it doesn't mention any 8 pin connectors.
http://www.scan.co.uk/Products/Produ...oductID=446788