Earlier today FUD Zilla claimed ATI's Radeon HD 4890 (RV790) is a new design, and not a higher clocked RV770, but a new report at PC Games Hardware says contradicts this. According to the German tech site, the upcoming RV790 only has higher core and memory frequencies and will compete against the NVIDIA GeForce GTX 260. The ATI Radeon HD 4890 is expected to hit retail stores on April 6 for around 230-240EUR.
Basis for the increased frequencies is the 55 nm production process, which has been quite perfected by now. 850 to 900 MHz appear to be possible for the RV790 GPU; the RV770 of the HD 4870 is clocked to 750 MHz. As the GDDR5 memory of the HD 4890 (Single) is regarded, AMD wants to reach 3,900 million transactions/s - RV770 based cards reach 3,600 MT/s. Those numbers indicate an increase in gaming performance of 8 to 20 percent, depending on game and sequence.
There's also a rumor about a dual-GPU Radeon HD 4890 X2 card, but it's unknown if AMD will invest time and money in such a prestige project. Perhaps an add-in board partner like Sapphire will be willing to launch such a card, like they did with the Radeon HD 4850 X2.