VR Zone claims NVIDIA will give its GeForce 9800 GX2 cards new G92-451 GPUs. These chips are pin-to-pin compatible and the site speculates these parts might be 55nm for better yield, lower cost and power.
Nvidia is planning to add a new G92-451 GPU to the existing GeForce 9800 GX2 cards based on G92-450 GPUs. However, the transition is almost invisible as it is pin to pin compatible and interchangeable with the existing GPUs without the need to update BIOS or drivers. The reason for change is due to improved manufacturing yields and ensuring continuity of NVTTM production supply.