It's more like an extension cable, I can't close the case if I plug the cables directly into the GPU.
It's actually this one:
http://imgur.com/a/34H0Kix
Not like the one in the first post, but it has the same connectors.
Exactly, just as an extension, but the problem is the one square pin on the female port.
UPDATE: Just plugged it in and it works fine. Thanks for the answer anyway. So, it is official that one different pin on the 6-pin to 6-pin adapter doesn't actually matter.