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Been looking at the r9 270 as its only for casual gaming
http://www.overclockers.co.uk/showproduct.php?prodid=GX-130-GI
The only difference between the X and none X is clocks, they're both 7870's.
OCUK's pic shows 2.
As does description.
I haven't seen any reviews for the Gigabyte card, but the 270 reviews say that there's a low power limit and so only 1x6 pin is needed. It could be a reference design thing.