Sorry, I guess original post wasn't clear.
The PSU ships with 2 cables - because it is a modular PSU, each cable has 2 connectors in this case.
1. Cable 1 has a 4+4 on one end, pretty sure that one should go to the mobo.
Cable 1 had an 8 pin (non-detachable) on the other end, which should go to the PSU.
2. Cable 2 also has a 4+4 on one end.
Cable 2 has a 12 pin on the other end, but only 8 of the pins have contacts. What is it for??