- Primochill Typhoon 3 + D5 pump (for performance reasons)
- Connect all computers to the same power strip
- Connect pump to powerstrip (if AC) or pump's PSU to powerstrip...

If ANY computer is on, then the powerstrip will need to be on, and thus the pump will be on. This is similar to a toggle switch, except it's safer.

- The fans can then remain powered by their computer's PSU.