Commentary to results
Im not sure if all these charts include final data, but if they do, then we have some mixed results. Sometimes one R9 290X can beat SLI or CrossFire configurations, sometimes its slower than R9 280X. One thing is certain though, this card will consume a lot of power (you can find these charts at the very bottom).
http://videocardz.com/47106/amd-radeon-r9-290x-review-charts-leak
Now I'm even more anxious to see the pricing for this card, could be less than what has been rurmored so far. Especially after the announcement of the 780ti and expected price drop of the 780.