25,000 watts at 120 volts is over 200 amps.  Unless you locate in a commercial space that is equipped for that sort of power, you will need the utility service upgraded.  If you are talking about locating in "a garage", that suggests residential for me.  Most homes in the US are on 100 or 200 amp service for the *whole house*.

That's a lot of heat to move too...  The power and cooling restraints will be more of a challenge than building and racking the rigs I suspect.

If you locate in a data center, usually 60+ amps of service per rack is no big deal, and they already have the environmentals taken care of.  You would just need to design around a standard rack-mount case, or build your own frames that fit in a standard 42" rack.