I am slightly inclined to agree with @don_svetlio. Slightly.
You could upgrade and get a GTX 970, however, I would also be inclined to upgrade your PSU as well. It is, in my opinion, THE MOST important part of any rig, gaming or not. You can compromise on the PSU to within a certain degree, but it's best to get a good quality PSU.
If you're going to upgrade your GPU, I would upgrade your PSU at the same time. You could forego it, but I REALLY wouldn't skimp on such a crucial part. It can kill (@don_svetlio, emphasis on the CAN, you don't have to throw out such convictions) your components very suddenly, so I would get a new PSU. Not just that, the quality of the DC output from the PSU may not be that good, leading to a shorter lifespan of your components. Something like an EVGA 550/650 GS/G2 are good shouts.
WTH Asus?
The other guy who said to stay away from the Strix is right.
Not only are the gaps on the pipes a no-no (thermal compound lodged between the pipes a heat magnet) but it seems like the outer pipes on both ends aren't even making any contact based on the lack of compound on them. Holy crap! That's horrible engineering/quality control.