I found this on Amazon and I just wan't to get the ASUS R9 280X DCUII TOP V2, but I don't know what the difference is between these cards.
They have different coolers and/or clocks, for ASUS you can check it at
http://www.asus.com/Graphics_Cards/AMD_Series_Products/
one is a triple slot and one is a dual slot. I think the dual slot one is better personally
Cheers.