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?
Here's another article on the 68xx series in Xfire
Xfire scaling was found to be 100% on 10 or the 19 games they tested, and remaining very high on the others. Nvidia and ATi seems to trade blows at different games tested, but it is evident that Ati has stepped up their Xfire drivers int he 6xxx series.