[LeifCarrotson]

Not feasibly.

If you really wanted to do it, the biggest processors have 40 lanes of PCIe. Intel's Xeon E5's can be dual-socket mounted, for a total of 80 PCIe lanes. Adding PCIe switching, like two Avago/PLX PEX9797s (see http://www.anandtech.com/show/9245/avago-announces-plx-pex97..., particularly the diagram at http://images.anandtech.com/doci/9245/Slide14.JPG) can get you there in the end.

But the sacrifice is that you actually only have 80 lines of PCIe, and it all has to be coordinated. Dual-socket computing does not quite double your processing power, and a switch adds latency. Your overall bandwidth will still be limited to what you have coming from the processor.