How Does FX Treat Your Graphics Card?
Does AMD’s flagship CPU really allow GeForce cards to run closer to their potential than Radeons? That conclusion is still a little difficult to reach, since the Radeon HD 7970 is faster than the GeForce GTX 680 in today's benchmark suite. We can still get there by comparing the results of a less-bottlenecked processor, however, and we can get even more information by comparing CrossFire to SLI. After spending way too much time poring over the data, the best illustration of CPU-to-GPU scaling occurred as I wrote this article’s introduction.
The above chart shows that, without significant CPU bottlenecks, two GeForce GTX 680s in SLI and a pair of Radeon HD 7970s in CrossFire offer similar performance. It also illustrates that this performance similarly comes not from having identically-performing cards, but from a slight scaling advantage favoring the slower GeForce GTX 680s when you put two of them together.
Our big revelation is that AMD’s FX-8350 performs 5% better in SLI than it does in CrossFire. When all else is made equal, AMD’s current flagship host processor really does favor Nvidia's graphics technology. Whoops.