Performance Summary Diagrams
First, let’s evaluate the efficiency of SLI technology with two overclocked GeForce GTX 670s.
Well, the two cards are much faster than the single one, especially in heavy applications and with enabled antialiasing, the performance benefits amounting to an average 69-71%. Sid Meier's Civilization V, Crysis 2, Total War: Shogun 2 and S.T.A.L.K.E.R.: Call of Pripyat are the games where we can observe the highest SLI efficiency – over 90%!
When a third card is added to the SLI tandem, the picture becomes more complicated.
3-way SLI technology is quite efficient in Metro 2033: The Last Refuge, Battlefield 3, DiRT Showdown, and in the heavier test modes of Aliens vs. Predator (2010) and Just Cause 2. However, even in these games the average performance growth is generally below 50%. In most other tests the 3-way SLI is only 20-25% ahead of the 2-way SLI configuration. The third graphics card even lowers the frame rate in the easier test modes of Tom Clancy's H.A.W.X. 2 and Crysis 2.
Now let’s compare the Zotac GeForce GTX 670 AMP! Edition and the Nvidia GeForce GTX 680:
As you can see, these graphics cards are very close to each other. The Zotac is an average 1 to 1.5% slower without antialiasing and 1 to 2.5% faster with antialiasing (thanks to faster memory) across all the tests.
We guess it’s also interesting to compare the two fastest single-GPU solutions available today: Nvidia GeForce GTX 680 and AMD Radeon HD 7970 GHz Edition. The latter being a new model, it serves as a baseline here.
We wouldn’t say that AMD is definitely on the winning side with the updated Radeon HD 7970. Everything still depends on the specific game and driver optimizations. For example, the GeForce GTX 680 is ahead in Lost Planet 2, Tom Clancy's H.A.W.X. 2, Hard Reset and the higher-quality mode of StarCraft II: Wings of Liberty whereas the AMD Radeon HD 7970 GHz Edition wins in S.T.A.L.K.E.R.: Call of Pripyat, Left 4 Dead 2, Metro 2033: The Last Refuge, Aliens vs. Predator (2010), Sid Meier's Civilization V and DiRT Showdown. Well, that’s not the last of our Radeon HD 7970 GHz Edition tests as we are going to write a review of its reference sample soon.