Was looking through my office window at the data closet and (due to angle, objects, field of view) could only see one server light cluster out of the 6 racks full. And thought it would be nice to scale everything down to 2U. Then day-dreamed about a future where a warehouse data center was reduced to a single hypercube sitting alone in the vast darkness.
IIRC, light speed delay (or technically, electricity speed delay) it’s also a factor, but I can’t remember how much of a factor.
It’s significant already. If I get the math right (warning, I’m on my phone in bed at 3am and it’s been 10 years) I think that a 1 inch chip running at 3GHz clock rate could, if you aren’t careful with the design of the clock network, end up with half a clock cycle physically fitting on the chip. That is, the trace that was supposed to move the signal from one end of the chip to the other, would instead see the clock signal as a standing wave, not moving at all. (Of course people has (tried?) to make use of that effect. I think it was called “resonant clock distribution” or some such)