I can't decide between the Gigabyte HD 7970 GHz edition or the Asus DirectCU II 7970, if there is a difference. There must be something that sets the Asus forward, at least where price is concerned.
because their DirectCU II is very good, but honestly, I'd probably go with the Gigabyte one if looks didn't matter (I really hate their blue PCB when I want an MSI-blue build) just because it has three fans and a massive amount of heatsink on there for them to cool, so you could probably run a very quiet fan curve and get similar cooling results.
is one more overclockable than the other?
Id say the Gigabyte is just because of the Cooling Solution, at max fans (100%) it will be loud but they say you wont be able to get the GPU temp past 43c, and it also Cools the VRM nicely.