According to technical specifications, it would suggest that twin Radeon HD 4770 would be about as quick as a single Radeon HD 4890. But then again, cards do not always scale linearly, or even predictably for that matter; much depends on driver optimizations. And because of this unpredictability, many have pondered, wondered and speculated about the performance of two Radeon HD 4770 cards in CrossFireX.
Well, you can stop wrecking your heads over this matter for we've tried it out ourselves and the results are pretty amazing and impressive.
We have a reference ATI Radeon HD 4770 on hand, and we were lucky enough to get our hands on the Sapphire Radeon HD 4770 (which is of standard clock speeds) to complete our CrossFireX setup. As for our test setup, the system is identical to the one we used in our Radeon HD 4770 review, and so are the benchmarks. However, this time we've thrown a Radeon HD 4890 into the mix as well as a GeForce GTX 260 Core 216. Here are some photos and then the results: