Stefan Mileschin

Back in September of 2014 AMD released their first Graphics Core Next 1.2 GPU, Tonga, which was the GPU at the heart of the Radeon R9 285. For all intents and purposes Tonga was the modern successor to AMD’s original GCN GPU, Tahiti, packing in the same 32 CUs and 32 ROPs, while other features such as color compression allowed AMD to trim the memory bus to 256-bits wide without a performance hit. With Tahiti slowly going out of date from a feature perspective, Tonga was an interesting and unprecedented mid-cycle refresh of a GPU.

However in the 14 months since the launch of the first Tonga product AMD has never released a fully enabled desktop SKU, until now. Radeon R9 285 utilized a partially disabled Tonga – only 28 of 32 CUs were enabled – and while it was refreshed as the Radeon R9 380 as part of the Radeon 300 series launch, a fully enabled version of Tonga only showed up in mobile, where in the form of the R9 M295X it was used in the 27” iMac. In its place AMD continued selling the Tahiti based Radeon R9 280 series for much longer than we would have expected, leading to an atypical situation for AMD where a card using the fully enabled GPU is only now showing up over a year later. In some ways Radeon R9 380X is a card we were starting to think we’d never see.

http://www.anandtech.com/show/9801/a...radeon-r9-380x