It means you only use half the 8 pin connection; that's why it breaks into two sections, for older boards that only have the 4 pin 12v connection. If you don't believe me, then I would write corsair and wait for a response. They should reply within a day. I'm surprised they don't have a separate 4 pin connection like my silverstone.
Every Corsair PSU that I have seen uses the "4+4" connector, unlike my two Antecs that have both 4 and 8 pin cables.