Out the top, then where?
If you were in the USA, you'd need to study Article 645 of the National Electrical Code, which covers your specific case.
Among other things, it requires that the air conditioning system be dedicated _only_ to the computer equipment, that the room be isolated, fire- wise and ventilation- wise, from the remainder of the building, and that your power wiring must be pretty completely jacketed in metal.
I.e., absent countermeasures required by the Code, the ventilation system provides a forced draft to any developing fire, common nonmetallic insulation constitutes fuel that also produces toxic smoke, and there's no shortage of heat sources from any single point of failure in an electrical power distribution system. All points of the fire triad are present or one mistake away.
Yes, it's been done. It's a good idea, from a cooling perspective. From other perspectives, a little caution would be appropriate. Check the Canadian equivalent of the NEC. Better, hire someone who knows it chapter and verse.
-Mike-