And that would be the non-X model. Aimed at the sub 280 USD price bracket the Tahiti GPU gas been respun. The product has been released to counter the NVIDIA GeForce GTX 760. Basically the R9 280 is a Radeon HD 7950 but comes with slightly higher clock speeds and PowerTune with boost technology. 

Since the product is based on the R7950 is has a 28 nm "Tahiti" chip that has 1792 Graphics Core-Next shader processors, 112 TMUs, 32 ROPs, and a 384-bit wide GDDR5 memory interface, that and  3 GB of memory.

The core clock frequency is 827 MHz while it can boost towards 933 MHz. The memory has an effective datarate of 5 Gbps. The R9 280 has a rather high 250W average board power as the R9 280X. You'll see several version from AMDs board partners in the weeks to come.