AMD's new Radeon HD 7790 plugs the mid-range gap between the S$180-200 Radeon HD 7770 and $255-335 Radeon HD 7850 cards. The Radeon HD 7790 utilizes a completely new GCN (Graphics Core Next) 28nm GPU, codenamed Bonaire. We take a look at it as well as two custom models from ASUS and Sapphire.