If you compare the X1950 PRO against the X1900GT based on the R580 core and that runs at 575MHz, will performs quite similarly, but the power consumption and heat dissipation on the R580 based X1900GT is far more greater. But if you compare the X1950PRO against the X1900GT that is based on the same chip (RV570), the X1950 PRO will be much faster in high resolutions due to it's faster core clock and slighly higher memory speeds.