If by "enough" you mean will it bottleneck a GTX 680? No. Even if you had any concerns you could always pick up an aftermarket HSF and overclock your i7
If you have the budget for a GTX 680 you might as well get a 7970 with a good cooler and be done with it. If you want to stay in the NVidia camp then follow ASHISH65 and get the GTX 670 and overclock it yourself, instant GTX 680.