3DMark Vantage isn’t a heavy test for today’s top-end graphics cards, let alone multi-GPU configurations, so we should only focus on the Extreme settings. The 2-way SLI built out of GeForce GTX 670s is highly efficient then, delivering an 80% performance boost. The 3-way SLI can only add 23% more. This cannot be explained by the platform’s limitations because the Performance scores are higher. Thus, 3-way SLI technology is just not as efficient as it should be.
The Nvidia GeForce GTX 680 comes out the winner in its race against the accelerated Radeon HD 7970. It has no rivals in 3DMark Vantage as yet. The Zotac GeForce GTX 670 AMP! Edition (1098/6608 MHz) is very close to the reference GeForce GTX 680, but can’t overtake it.
Nvidia’s multi-GPU technology does better in 3DMark 2011 where the 2-way SLI configuration is up to 96% faster than the single card and the 3-way SLI adds 36% more. Of course, the latter number may not seem high enough to justify the addition of a third graphics card, yet the confident performance of our three GTX 670s must be noted anyway.
The Nvidia GeForce GTX 680 is again ahead of the AMD Radeon HD 7970 GHz Edition. The Zotac GeForce GTX 670 AMP! Edition stops 4% short of the leader’s result.
Unigine Heaven Demo
The GeForce GTX 670-based multi-GPU configurations look good in this test, too. At the lower-quality settings the second card adds 44% and the third card adds 49% more to the single card’s result. And at the higher resolution with 8x antialiasing they add 88% and 33%, respectively.
There are no changes in the standings of the Nvidia GeForce GTX 680, AMD Radeon HD 7970 GHz Edition and Zotac GeForce GTX 670 AMP! Edition except that they all deliver the same results at the highest settings.
S.T.A.L.K.E.R.: Call of Pripyat
The first game on our list makes it clear that the third card in our SLI configuration isn’t worth the trouble of buying and installing. While the 2-way GeForce GTX 670 SLI can increase the frame rate by 68 to 96% compared to the single GTX 670, the 3-way SLI is a mere 19-23% ahead of the tandem. The three GTX 670s are even slower than the two at the lowest settings, which must be due to the lower graphics subsystem load and higher overhead associated with 3-way SLI.
As opposed to the three semi-synthetic benchmarks, the AMD Radeon HD 7970 GHz Edition scores a win over the Nvidia GeForce GTX 680 when it comes to actual games. The gap is just a few frames per second, though. The Zotac GeForce GTX 670 AMP! Edition is somewhere in between the reference GTX 670 and 680 in performance.
Left 4 Dead 2
The top-end graphics hardware we’ve got today can only be compared in Left 4 Dead 2 at 2560x1440 with anisotropic filtering and 8x antialiasing. At such settings, the two GeForce GTX 670s are 79% ahead of the single card whereas the third GTX 670 adds only 12% to that. So again, the third card’s resources seem to be wasted.
Metro 2033: The Last Refuge
The two multi-GPU configurations boast exemplary scalability in Metro 2033: The Last Refuge: up to 73% in 2-way SLI and up to 93% in 3-way SLI mode. Running ahead, we can tell you that these are the best results the 3-way SLI configuration could achieve in our tests. That said, we have to draw your attention to the low bottom speed which doesn’t grow up along with the average frame rate, so playability is questionable even on the multi-GPU configurations.
The NVIDIA GeForce GTX 680 falls behind the AMD Radeon HD 7970 GHz Edition and is also somewhat slower than the pre-overclocked Zotac GeForce GTX 670 AMP! Edition.