As per the reference obtained by Expreview, Nvidia is working on single-printed circuit board iteration of dual-GPU GeForce GTX 295 graphics chip. The design of the new iteration is currently dubbed as P658.
The dual GTX 295 had two PCBs and design dubbed as P656. In out tests of the Asus GeForce GTX 295, we found the new dual-GPU monster card was power efficient and performed well; thanks to the 55nm fabrication process.
With the new single-PCB design, Nvidia is looking forward to use two GT200 series GPUs on that single PCB. For memory, both GPUs will use 448-bit interface found in the GTX 295 as well.
Length of the PCB will be 266.7 mm which will require working on the cooler, power supply points and the wiring. In terms of performance, the clock speed of GTX 295's graphics core remains unchanged. Even the 6-pin and 8-pin power connectors will remain the same.
If this isn't the new single-board GTX 295, then the P658 might be Nvidia's PCB design for future dual-GPU cards. We don't know it yet since Nvidia refrains on commenting about unreleased or unannounced products.