X-bit Labs claims you shouldn't expect any radical performance boosts from the upcoming ATI Radeon HD 4890 (RV790) graphics card. The site was told that the RV790 is nothing more than a RV770 GPU with higher clockspeeds.
Performance increases of the graphics card that is projected to be called ATI Radeon HD 4890 over the existing Radeon HD 4870 1GB should not be high as the difference between two products will be increases of clock-speeds. In case the graphics card designer decides to release ATI Radeon HD 4890 X2, performance gain should be modest as well.
"This is exactly the same situation as in the case of transition from ATI Radeon 9800 Pro to ATI Radeon 9800 XT back in 2003, performance gain will not be massive," a person wished to remain anonymous said.