Well between the two some games favor one card over the other. For example, Battlefield 3 favor Nvidia cards so it will have higher frames than an AMD card.
Performance wise the GTX 670 is still stronger in most games, will be higher when overclocked
http://www.anandtech.com/bench/Product/598?vs=508
But when you have an overclocked 7970 or the 7970 GHz Edition, the 7970 beats the 670 (non overclocked).
For the price though, GTX 670 is the best card for the money.
The two best card for temps and performance is here:
Quote :
All-Around Best GeForce GTX 670: Gigabyte N670OC-2GD
Gigabyte's card is quiet at idle and not too loud under load. Its cooling performance at idle, during normal desktop work, and during gaming is even better than Asus' card. It ties Zotac's effort for the lowest temperature at idle, but achieves its goal at a mere 20% fan duty cycle. When we configured it to cool our card down to 70°C, its sound level was still acceptable.
This is the slimmest card in our test, it weighs the least, and is even suitable for SLI configurations on motherboards with a just a single-slot gap between 16-lane interfaces. Unfortunately, that's pretty common. Although the N670OC-2GD doesn't include the highest overclock, it's currently selling online at the same $400 price point as completely stock reference cards. And that's with the Windforce 3X cooler. That combination cannot be beat.
Source:
http://www.tomshardware.com/reviews/geforce-gtx-670-test-review,3217-16.html
Hope that helps
