An interesting set of benchmarks has been posted by a user called Grant Kim, apparantly he has access to a AMD R9-290X and has posted a handful of benchmarks. Now before we begin I have no clue about the validity of the specs and benchmarks.
The post originates from TPU:
The GPU core is clocked at 800 MHz. There is no dynamic-overclocking feature, but the chip can lower its clocks, taking load and temperatures into account. The memory is clocked at 1125 MHz (4.50 GHz GDDR5-effective). At that speed, the chip churns out 288 GB/s of memory bandwidth, over its 512-bit wide memory interface. Those clock speeds were reported by the GPU-Z client to us, so we give it the benefit of our doubt, even if it goes against AMD's ">300 GB/s memory bandwidth" bullet-point in its presentation. Among the tests run on the card include frame-rates and frame-latency for Aliens vs. Predators, Battlefield 3, Crysis 3, GRID 2, Tomb Raider (2013), RAGE, and TESV: Skyrim, in no-antialiasing, FXAA, and MSAA modes; at 5760 x 1080 pixels resolution. An NVIDIA GeForce GTX TITAN was pitted against it, running the latest WHQL driver. We must remind you that at that resolution, AMD and NVIDIA GPUs tend to behave a little differently due to the way they handle multi-display, and so it may be an apples-to-coconuts comparison. In Tomb Raider (2013), the R9 290X romps ahead of the GTX TITAN, with higher average, maximum, and minimum frame rates in most tests.