That's because this tweet is written to maximize engagement. Number 3 uses a screenshot of some other random tweet that says all people of indian descent in the US are "agents" (5.1 million people).
There is also NVLink c2c support between Nvidia's CPUs and GPUs that doesn't require any copy, CPUs and GPUs directly access each other's memory over a coherent bus. IIRC, they have 4 CPU + 4 GPU servers already available.
There is a space between the numerical value and unit symbol, even when the value is used in an adjectival sense, except in the case of superscript units for plane angle.