CrossFire: Crysis 3 At 7680x1440
The same sort of reversal affects Crysis, and a peek at the temperature logs reveal a pattern of heating up to 94 degrees or so, maxing out the fan at 40%, and then necessarily dropping clock rate in order to maintain stability.
Although the bars flip-flop, looking at frame rates over time shows that two GeForce GTX Titans and two Radeon R9 290Xes are quite competitive. Switching on AMD's Uber mode would really benefit these boards with additional cooling capacity. The thermal solution is simply too loud for that, though.
Here's more evidence that CrossFire likely needs some additional work. This is with frame pacing enabled, and yet the paired-up R9 290Xes demonstrate fairly high worst-case variance, more than doubling what we observe from one card. If you click on the following link, you can see what this looks like in a raw chart of frame times. The deep red line is a tell-tale indicator of more variance compared to the narrower pink line (or Nvidia's lines, which are also pretty clean).
- AMD: We're not aiming for the ultra high end.
I think Nvidia just got trolled.