1. heat (dissipation)
2. power
3. network bandwidth
4. cosmic rays (shielding)
5. part failures (with so many parts, there’s always something broken
6. eol parts (lifecycling in 3-5 yrs avg)

They are all challenges that can be overcome. But at what cost. Consensus is that economically it seems hilariously unviable. Datacenters tend to have to make their money back within about 3 years. The 3 year make money back issue is also why I believe the AI DC buildout is such a high risk gamble/bubble. In a year or two, all that hardware they made a year ago will need to be replaced. You just redo the whole investment again…