CrossFire: BioShock Infinite At 7680x1440
R9 290X beat GeForce GTX Titan at 1920x1080, 2560x1440, and 3840x2160. So what the heck happened at 7680x1440? Check it out:
Radeon R9 290X is getting beaten up by the workload with one card. With two installed, it spends most of the run just sitting at 727 MHz (72% of its rated clock rate). Now, again, I have to concede that achieving this performance level against $2000 worth of hardware from Nvidia is still phenomenal. But it's such a shame that AMD can't get more from this GPU. At any rate, let's look at performance over time.
The discrepancy between Titan and 290X naturally grows in a multi-card configuration, though the $550 board from AMD still has plenty to be proud of.
Enabling CrossFire over PCI Express through a DMA engine works brilliantly for circumventing the bottleneck imposed by AMD's top bridges. However, this mechanism might not be optimized yet. Our frame time variance numbers are by no means problematic. But they are notably higher than what Nvidia can do in SLI.