a report has come up that the company will be releasing a HD 7790 GPU card in April in an effort to bridge the gap between the HD 7770 and HD 7850 graphics card. It was further stated that unlike these cards, the AMD HD 7790 Radeon will be based on the Bonaire XT core. This will be the first AMD GPU that will be based on GCN 2.0 architecture which is said to be used for the AMD 8000 series GPU as well.
the performance of the HD 7790 is so impressive that AMD have asked manufacturers not to have a non-reference/overclocked version of the cards. The reason that they’ve asked to do so is because AMD has fear that doing so may surpass the performance of HD 7850, not only defeating the purpose but also eventually crippling HD 7850′s sales.
Overclocked version will be better than HD 7850 but the price is cheaper than HD 7850? That's AMD for you.