Check on the corsair site to see type number cables you need. It's probably type 4. You can buy an additional PCIe cable from the Corsair website for £3.99
If the worst comes to worst I can let you have one. I have tons of them lying around. If you go to packlink and arrange Hermes to collect the parcel from me it should be about £4. I only have type 4.
Incidentally, some of the cables I have came from RM650's so I am pretty sure your cables are Type 4 but I am not saying that cus I don't want to implicate myself!!
Oh I just read your last post. Yes, I can understand. I have substituted cables before and know that its seriously worrying. Yes, it's a lot of money but the consequences of getting wrong are too horrible to contemplate. If you look at the Corsair website forum, plenty of people do get it wrong and it wipes out their entire PC and PSU in one impressive puff of smoke.