I'm surprised this hasn't been done before; a monolithic wafer can achieve denser interconnects, and is arguably simpler than a multi-chip module. On the other

I'm surprised this hasn't been done before; a monolithic wafer can achieve denser interconnects, and is arguably simpler than a multi-chip module. On the other hand, multi-chip modules can combine the working chips in low-yield wafers, whereas a monolithic wafer would likely contain many failed blocks, uselessly taking up space / distancing the working chips. Cooling isn't really a problem, as the TDP scales with area as in other chips. Water cooling or heat pipes can transport the heat away to a large heat sink. 3D / die-stacked chips have a harder cooling problem, potentially requiring something like an intra-chip circulatory system.