First, let’s measure the difference between the GeForce GTX 680 and the dual-GPU GeForce GTX 690 at their default clock rates:
We can see the same trend throughout all the tests: the gap between the two cards grows larger at higher graphics loads. The yellow columns are almost always higher than the violet ones, which means that the GeForce GTX 690 shows its best when you enable antialiasing and highest resolutions. The average advantage of the GeForce GTX 680 over its junior cousin amounts to 54-72% at 1920x1080 and to 62-78% at 2560x1600. But if we take the most resource-consuming applications, the gap will be 90-95%!
The next pair of summary diagrams compare the default GeForce GTX 690 with the CrossFireX tandem of Radeon HD 7970s clocked at 1000/5800 MHz:
We’ve got two multi-GPU technologies competing here. We’ll discuss the efficiency of CrossFireX in more detail in our upcoming report, but we can note here that the GeForce GTX 690 easily wins where CrossFireX doesn’t work or works inefficiently (and there are quite a lot of such applications on our list including Battlefield 3, Crysis 2 at the high-quality settings and Batman: Arkham City). The slightly overclocked CrossFireX tandem is ahead in three games: Aliens vs. Predator (2010), Sid Meier's Civilization V and Total War: Shogun 2 (the GeForce series has got slower in the latter game with the recent drivers). In the rest of the games and tests the two solutions deliver similar performance. If we calculate the average across all the tests (which is not quite a correct way of comparison, we must admit), the default GeForce GTX 690 is ahead of the two Radeon HD 7970s overclocked to 1000/5800 MHz by 5-12% at 1920x1080 and by 1-15% at 2560x1600.
The AMD Radeon HD 79xx series features high overclocking potential and a linear correlation between performance and clock rates. Today we've overclocked our GeForce GTX 690 from 915/6008 to 1085/7588 MHz (+18.6/26.3% without frequency boost), so let’s see what performance benefits this overclocking provides:
Comparing the results at 1920x1080 and 2560x1600, we can see a higher performance growth at the higher resolution. The overclocked GeForce GTX 690 is faster by 8-12% at 1920x1080 and by 11-15% at 2560x1600. The heavier the test, the bigger the performance growth is. The Radeon HD 79xx series has a stronger correlation between performance and frequency at overclocking, but the GeForce GTX 690 is a multi-GPU solution as opposed to the single-GPU Radeon HD 7970.