+1 to Sunius and Sumukh. For an alternative, the GTX660 is almost as fast (you'd lose around 10% on average) but a lot cheaper. Only other thing I'd mention is that I've owned three Sapphire cards, and all three died within six months after warranty expired. Just something to bear in mind! I won't be buying a fourth.
If you plan on playing on resolutions above 1080p, then go for Radeon 7950. It's meant for high resolutions.
GTX 660 ti is meant for 1080p and will certainly get almost the same fps as the 7950.
As the others has mentioned then you have to remember the great technologies that Nvidia provides. Though they might fate away soon because of AMD has begun to 'steal' some of them. Just look at the boost technology that AMD suddenly just added to their lineup of the 7000 series a while after the Nvidia 600 series got launched.
Yeah nVidia cards have a huge advantage with adaptive v-sync. AMD have nothing to compete with that (best I can do is combine standard v-sync with triple buffering, but it's an inferior solution). The Radeon 8000s are gonna need to incorporate something like adaptive v-sync if they want nVidia to lose that advantage.
Well I'd say it will perform better :-) Not purely interms in frames/second without v-sync, but interms of smoothness and responsiveness due to:
- nVidia adaptive v-sync meaning framerates are unrestricted below 60fps. If you use v-sync on the Radeon and framerate drops to 55fps, the Radeon will sync it down to 30fps. That's a big loss. Seems hard to believe (it really is a crappy solution) but I can post a load of links if you need proof. Take a look at this anyway http://www.hardocp.com/article/201 [...] y_review/3
- frames/second is a pretty crude and oversimplified method of testing performance anyway. This has been mentioned by a few people lately in the forums but I didn't know what they were talking about. So I did some research on it, check this out: http://techreport.com/review/23981/radeon-hd-7950-vs-ge...
As for which card, I'd take the 2GB if you're planning on SLI in a year or two when prices have dropped. If you're sticking with a single card (which is what I'd do), 3GB won't make a difference, but if prices are close then you might as well.