Some variance in performance is to be expected, AMD says
Following the launch of AMD's Radeon R9 290X graphics card, a handful of sites noticed that the sample cards sent to the press were performing faster than their retail counterparts. It has been suggested by some that AMD essentially cherry picked the best cards for reviewers, though AMD says there's a valid reason for the performance gap. According to AMD, it has to do with the new PowerTune mechanism in the R9 290 Series.
"Based on feedback from the enthusiast community, we’ve implemented an all new PowerTune mechanism in the AMD Radeon R9 290 series that exploits the full capability of the individual GPUs rather than clamping performance to a least-common-denominator type of capability level. This has the advantage of improving overall performance but does result in some degree of performance variability," AMD said in a statement to Legit Reviews. "These changes will also result in some degree of run-to-run test variability based on environmental and operational conditions in un-controlled test environments."
AMD added that the performance variability of retail cards shouldn't be significantly different than press samples and that it should occur both above and below what reviewers recorded, "however it appears that most reported performances are biased towards the low side." That being the case, AMD said it is "actively investigating" the cause and promises to provide another update at the conclusion of its investigation.
In the meantime, be sure to check out our benchmark run of the 290X.