FYI, the 7950 is still not faster than a 670 at stock (I've had both, a reference 670 and a "boosted" 7950 at 1000/1250). This is with the newest drivers from both companies. Even though we hear a lot of about the AMD gains, we don't hear as much about the nvidia gains... they've been releasing new drivers every month.
reference 670 in Heaven: 42-43 FPS consistently
7950 @ 1000/1250: 41-42 FPS consistently
However, the difference is minimal, and if you're on a budget, you won't see the difference between a 7950 and a 670. Do realize the 670 is quite a bit leaner on power and size, if you need that. Also once you get the 7950 up to 1175/1575, it gets closer to around 46-47 FPS, which is 7970 territory. This overclock wasn't stable for me in games, however.
Also, in my experience, AMD cards are more prone to coil whine as well. Both my 7970 and my 7950 whines like crazy, the 660 and 670 never whined for me.
I've also had a 7970 GHz, and I'll be honest, between the 7950 and 7970, I don't really see a difference. Stick with a 7950 or 670.
Edited by CiTRxJ - 3/11/13 at 1:36pm