CrossFire Scales Spectacularly
While past reviews have shown that big multi-GPU performance gains are usually limited to more mainstream cards, today’s CrossFire results make a far better-than-expected impression.
AMD’s Radeon HD 6950 is anything but low-end, and yet its second card provides a huge 92% lead over a single board. Almost as impressively, a third card delivers an impressive 27% lead over two cards at “only” 2560x1600. We could expect even better results at higher resolutions, if only this lab had the monitors for that test. That’s why I just expensed two more 2560x1600 displays to support additional testing (just kidding, boss)!
Fears of three-way CrossFireX not being supported by a variety of games were almost put to rest when only a single game, Aliens vs. Predator, didn't realize any scaling improvements when we added a third card. While we still have minor concerns about what other games might suffer similarly (after all, AMD couldn't get F1 2010 working with anti-aliasing until zero-hour for our Radeon HD 6990 review), no performance gain in only one of five tested titles gives us a great deal of confidence in the company's compatibility efforts moving forward. Aliens vs. Predator is the one game where SLI showed its best scaling, a fact that we find odd given that this is not a “TWIMTBP” title.
CrossFire came out with a huge overall scaling lead over SLI, and removing the one title that didn’t reflect that average would have made the lead even bigger. Superior scaling allowed two mid-priced Radeon HD 6950s to approximate the performance of two higher-cost GeForce GTX 570s, while three HD 6950s took the performance win over three GTX 570s.
If CrossFire’s value-oriented victory in two-way and performance win in three-way configurations weren’t enough to convince us, the Radeon HD 6950's lower power certainly did. AMD started out with the highest efficiency at one card, and superb multi-GPU scaling allowed its efficiency to increase with every card we added. When’s the last time adding parts made your machine more efficient?