CrossFire Scaling Results: 3DMark And Crysis
3DMark shows the horrible effect of putting a high-performance graphics card in a low-performance slot, as two Radeon HD 5870 graphics cards consistently beat the P55 three-way configuration.
Yet 3DMark as a pure synthetic doesn’t show us how bad adding a third card in x4 mode can really be. For that, we could look to the most difficult game in our arsenal, which is Crysis.
Three cards are worse than two when paired with the P55. But also notice that two cards perform far better with the X58 than with the P55 in the Crysis benchmarks. This phenomenon is certain to be a limitation with CrossFire on x8 slots, although we expect it will appear only with super-bandwidth-hungry titles.
The X58 continues its lead at very high details and 4x AA, at least until we reach 2560x1600. We’ve seen the problems with running this last combination of settings on multi-card arrays several times in the past and are almost ready to ignore the setting.