Apart from the CPU-dependent Performance mode, 3DMark Vantage shows that both CrossFireX configurations are 76-83% faster than their single counterparts. We can also note that the Radeon HD 7970 CrossFireX is a mere 7-13% ahead of the Radeon HD 7950 CrossFireX.
The multi-GPU solutions can show their best in this more resource-consuming version of 3DMark, outperforming the single cards by 79-82% in the Performance mode and by 95-96% in the Extreme mode.
Unigine Heaven Demo
The two CrossFireX tandems are close to their maximum theoretical efficiency in this test, beating the respective single cards by 96-98%.
S.T.A.L.K.E.R.: Call of Pripyat
The multi-GPU tandems only show their best in S.T.A.L.K.E.R.: Call of Pripyat when we enable antialiasing together with the 2560x1600 resolution. It is then that we can observe a 95-100% increase in performance which is most welcome since the average 40 fps of the single Radeon HD 7970 is obviously not enough. The CrossFireX configurations are less efficient in the other graphics modes as they are limited by the performance of the platform at large.
Left 4 Dead 2
Left 4 Dead 2 doesn’t really need top-performance CrossFireX configurations, but even here the two Radeon HD 7970s are 80% faster than the single such card at 2560x1600 with antialiasing turned on.
Metro 2033: The Last Refuge
Radeon HD 7970 and HD 7950 based CrossFireX tandems are quite useful in Metro 2033: The Last Refuge. Although the performance benefits are far from record-breaking (65-78%), they are still tangible. Take note of the low bottom speed, though. That's the biggest problem with the multi-GPU technologies from both AMD and Nvidia.