The cable in the is a 6-pin to 6+2 pin adapter. So you'll need to just plug in the 6-pin part of the 6+2 and will have a 2-pin hanging of the cable and extension.
Okay I understand this. But I want to use a premium cable because this is a higher-end build. So a 6-pin+2 extension cable would work if I connect both the 6-pin+2 cable and 6-pin+2 extension? I don't believe there would be any harm in doing this.