OK,looking at the 2, the HIS has faster ram, so thatll possibly help, as itll provide more bandwidth, which means, IF the cards needs to draw textures faster, it can, but it also has to be togther with the core, and how fast the core can produce the data.
Im not familiar enough with these cards, as to their weak parts, but having faster ram is good, but only if it can be used. +1 to HIS
They both have the same core speed, so no advantage either way. Since Im not familar with these particular cards, see if theres a power requirement difference, if not and the pricing is close to the same, go with the HIS, as its cooling solution is usually very nice, quieter, and more effective, and can even draw less power. I think the higher speeds on the ram would benefit you, as these cards are somewhat bandwidth limited. It wont be a huge advantage, but could make a difference or 2, but again, both good cards