..."At the end of June, in Spain, we were introduced to a new series of 48xx graphics cards from ATI. We saw then only RV770PRO (4850) but at this moment 4870 (RV770XT) is also available. Even though our sources from AMD didn't unveil why 4870 wasn't shown on launching, we assume that some problems with quantities of available GDDR5 memory occurred. Considering that 4850 uses GDDR3 memory, it is no surprise that many retailers had them on stock. ATI 4870 will be sold, in beginning, exclusively with GDDR5 memory (this is the first graphics card that uses this memory) but AMD leaves a possibility that some innovative partner might launch later version that uses GDDR3 memory."...
_______
Source: InsideHW
