PCIe express interface --> slow memory transfer
Well depends on how they configure it and how many lanes. Could be multiple chips & memory on a single card with internal PCIE switch. While not ultra fast it would be still pretty fast. PCIe 3.0 w/ 16 lanes is 16GB/s. The chip could support more than 16 lanes.
The only real advantage to GPUs is x86 instruction sets in the cores which may allow for easy porting of code to the offboard "CPUs", but really, this is basically a GPU with slightly different architecture.
I agree. The line between CPU & GPU is betting blurred. CPU becoming more GPU like, the rise of APU (hybrid chips), GPU gaining general purpose computing and moving to more complex "shaders" (more like processing engines).
This would have an advantage over GPU as all of the die is dedicated to computing. The average GPU "wastes" about 30% of its die for non-shader related functionality. Of course GPU are so powerful that they overcome this inefficiency w/ pure brute force but a compute engine could be very interesting.
Many AMD GPUs are already faster than this, for instance 5970 and 6990 can pull 1 TFLOPs.
Well 5970 is only 0.98 TFLOPs in DP. The 6990 is 1.278TFLOPS but that is w/ 2 chips.