Fudzilla: "AMD recently rolled out its latest RV790–based card running at 1GHz, and the reason why this card is so special is obvious – the dream of 1GHz on your graphics card is now a reality. This GPU is the central point of the Radeon HD 4890 and its GDDR5 memory helps in achieving 1.6 TeraFLOPs.
Let us recap – the RV790 core has been announced in the beginning of April 2009, and it quickly found its place in AMD's best single GPU graphics card. The RV790 runs at 850MHz, which is a significant improvement over the HD 4870's 750MHz. Of course, the HD 4870 comes from a generation of GPUs that was announced in June 2008."