The first pair of summary diagrams shows the efficiency of CrossFireX technology for two Radeon HD 7970 cards clocked at 1000/5800 MHz in comparison with a single such card at the same clock rates:
We don’t see a consistent increase in performance here. CrossFireX even doesn’t work at all in Battlefield 3 and when antialiasing is enabled in Crysis 2. On the other hand, this multi-GPU technology can double the frame rate where it is supported on the software side and is not limited by the performance of the platform. This performance boost is quite useful in many applications, especially at 2560x1600. The two Radeon HD 7970s in CrossFireX mode are ahead of the single such card by an average 56-72% at 1920x1080 and 65-76% at 2560x1600.
The same goes for the Radeon HD 7950s:
This pair of diagrams is generally the same as the previous one. The Radeon HD 7950 CrossFireX (at 900/5500 MHz) is 10-15% slower than the Radeon HD 7970 CrossFireX (at 1000/5800 MHz).
Finally, there are a couple of diagrams that compare two versions of the GeForce driver for the GeForce GTX 680 card: 300.99 beta and 301.24 beta.
The new driver boosts performance in Total War: Shogun 2 (in both test modes) and in Crysis 2 (without antialiasing). There are also some performance benefits in Batman: Arkham City and Hard Reset.
We measured the power consumption of computer systems with different graphics cards using a multifunctional panel Zalman ZM-MFC3 which can report how much power a computer (the monitor not included) draws from a wall socket. There were two test modes: 2D (editing documents in Microsoft Word and web surfing) and 3D (the benchmark from Metro 2033: The Last Refuge at 2560x1600 with maximum settings). Here are the results:
We guess it’s no secret that a computer with two top-end graphics cards needs a high-wattage power supply. The numbers make it clear enough. For example, the CrossFireX configuration built out of two slightly overclocked Radeon HD 7970s together with a well-overclocked six-core Intel CPU needs a 750-watt or higher PSU whereas two Radeon HD 7950s can be satisfied by a 700W PSU. Comparing the CrossFireX configurations with their single-GPU counterparts, we can see that adding one Radeon HD 7970 (1000/5800 MHz) increases the power consumption of the system by 214 watts whereas one Radeon HD 7950 (900/5500 MHz) adds 162 MHz. The system with a non-overclocked GeForce GTX 680 is the most economical here.