The GPU frequency remains almost unchanged (650MHz vs. 625MHz for the X1900 XT), only the usage of GDDR4 memory is a real new feature for this graphic card, providing a theoretical 60GB/s memory bandwidth.
But as one would have expected it, adding such GDDR4 modules to a "aging" GPU does not turn it into a 3D games killer. Performance gains are minor, but high enough to give ATI back the pole position of the race between manufacturers of the fastest graphic card.
This new updated version of the Radeon XT1950 XT should not be available for Mac.
A special message to ATI executives: It is about time that you update your current Mac Edition graphic card retail models, because it starts to look like a perfect Museum for old graphic cards exhibiting aging relics.
