Two GeForce GTX 670s In SLI
As you start sliding down the price ladder, adding a second card right away or somewhere down the road becomes a more attractive (and more realistic) proposition. Paying $800 for a couple of GeForce GTX 670s is still a lot of money, but $400 now and as much or less in a few months doesn’t sound as bad.
How, then, do a pair of GeForce GTX 670s perform compared to just one?
At 2560x1600 with graphics details cranked up, a second GeForce GTX 670 can turn marginal playability into a smooth experience. If you’re only gaming at 1920x1080, there’s really not much reason to add a second board. But as you start exploring 30” screens or multi-monitor gaming, a configuration like this makes a lot more sense.
Dividing those numbers into each other, we see that the best-case is Battlefield 3, where a second GeForce GTX 670 nearly doubles performance. Metro 2033 and WoW are both worst-case scenarios in our suite, where the second board boosts frame rates by 72 or 73%.
And now, the title match. Two GeForce GTX 670s against a pair of Radeon HD 7970s.
Five times out of six, the 670s are faster. The sixth is Metro 2033, where two Radeon HD 7970s are about 18% faster. Even in World of Warcraft, though, where Nvidia’s cards are more than 50% faster, performance is high enough on both setups that the experience is fluid.
One thing to keep in mind, though: Radeon HD 7970s are scalable up to four cards (as are GeForce GTX 680s). Nvidia is limiting its GTX 670s to three-way SLI.
I don’t see that as a problem, since the market for four-card configurations is diminutive.
Update (5/11/2012): Reader jaquith noticed that EVGA's box art listed four-way SLI as a feature of the GeForce GTX 670. We went back to Nvidia for comment and received word back that the packaging would need to be changed. A short time later, a new message indicated that a future driver will, in fact, add four-way SLI support to the GeForce GTX 670s. Apparently, this is a matter of validation that Nvidia still needs to perform, not a technical issue with the hardware or software.