Since it is already clear that R9 280X is pretty much the standard Radeon HD 7970 GHz Edition with a few tweaks in clocks it is possible to make it into the R9 280X via a simple BIOS update.
All you need is to somehow get your hands on a BIOS sample from the R9 280X, which will most likely be available for download, and update your own Radeon HD 7970 GHz Edition. Of course, the big problem are not the clocks, which are around 50MHz different depending on the version and model, but rather the whole new Powertune Boost, or to be precise, a different Powertune Boost setting.
We did try it and it simply works, but we are still in process of testing the new HD 7970 GHz Edition turned R9 280X graphics card. There are also a couple of differences in display outputs, but hopefully everything will work like charm.
Source: ocaholic