Maybe its just a reference design 7970, which sucks
I dont really know your system, so maybe a high end card might be bottlenecked, but if you ask me, pick a really beefer 7950, like an XFX or Sapphire with dual fans. These cards have a huge overclocking headroom so you can match or surpass a 7970 with no sweat (people report achieving 1200 to 1400Mhz stable without overvolt on 7950 Sapphire).
Nowadays these cards go out for about 360 to 380 USD, so if you find one that you like, will probably be a better choice than a 660Ti (which is an awesome product anyway, dont get me wrong) because the difference is just about 50USD and the potential from a 7950 is great for that minuscule diff.
If you dont feel like going High End, then pick the 660Ti (mid/high end because of its limited overclock) but I can tell you, its likely their prices will drop, so I voted for the WAIT option.