HD7870 - Screen flickering/Turning black

Recently bought a 7870.

Every time I started a game, the entire screen would flicker really badly and sometimes turning black.

1. Thought it was Windows 8 fault, since I only tried it on two games and no one seems to have a problem with this card on Windows 7, so I reinstall Windows. Still flicker.
2. Tried different CCC version ranging from 12.8 to even the latest 13.2 beta. Still flicker.

Came across a post somewhere about cables turning bad, so before changing out cables, I, just for the sake of it, tried plugging it into the other miniDP port.(7870 came with 2 miniDP)

Andd   it works!! No more flickering nor turning black.

My question is should I exchange my card because it has a faulty port? or is the underlying problem somewhere else (cable, driver, system)??

Thanks.