from DailyTech - Don't Get Too Accustomed to GDDR4: Qimonda Ships GDDR5 SGRAM
Global memory supplier Qimonda today announced that it is has shipped the industry’s first 512MB Graphics Double Data Rate (GDDR5) samples to partners and customers. GDDR5 SGRAM is the successor to GDDR4 SDRAM, which has yet to completely overtake GDDR3 SDRAM.
GDDR5 features data rates at 20GByte/s per component. This is double the bandwidth of the fastest GDDR3 memory.
GDDR5 operates using two different clock types. One clock type that GDDR5 comes with is a differential clock (CK), where address and command inputs are referenced. The other clock type that GDDR5 uses is the forwarded differential write clock (WCK), which operates at twice the frequency of the CK. Read and write data are referenced to the WCK.
Each write clock of GDDR5 SGRAM is assigned to two bytes.
High end graphics cores in development today, NVIDIA's next-generation architecture and AMD's R700, would be the first graphics cores capable of utilizing the new signalling required for GDDR5.
Click the link above for more. I wonder how this will affect the recent release of GDDR4, and how overclockable it will be. Apparently the memory has 2 different clocks... that should shake OCing up a bit. Other things mentioned are power saving features, particular memory I/O throttling.